yamaha 4ac 5c manual

OWNER’S MANUAL

4AC5C

6E3-28199-R1-E0

U6E3R1E0.book Thursday, March 2, 2006 9:44 AM

Read this owner’s manual carefully before operating your outboard motor.

U6E3R1E0.book Page 1 Thursday, March 2, 2006 9:44 AM

Important manual informationEMU25101

To the ownerThank you for choosing a Yamaha outboardmotor. This Owner’s Manual contains infor-mation needed for proper operation, mainte-nance and care. A thorough understanding ofthese simple instructions will help you obtainmaximum enjoyment from your new Yamaha.If you have any question about the operationor maintenance of your outboard motor,please consult a Yamaha dealer.In this Owner’s Manual particularly importantinformation is distinguished in the followingways.

The Safety Alert Symbol means AT-TENTION! BECOME ALERT! YOUR SAFE-TY IS INVOLVED!

WARNINGEWM00780

Failure to follow WARNING instructionscould result in severe injury or death to themachine operator, a bystander, or a per-son inspecting or repairing the outboardmotor.

CAUTION:ECM00700

A CAUTION indicates special precautionsthat must be taken to avoid damage to theoutboard motor.

NOTE:A NOTE provides key information to makeprocedures easier or clearer.

Yamaha continually seeks advancements inproduct design and quality. Therefore, whilethis manual contains the most current productinformation available at the time of printing,there may be minor discrepancies between

your machine and this manual. If there is anyquestion concerning this manual, please con-sult your Yamaha dealer.To ensure long product life, Yamaha recom-mends that you use the product and performthe specified periodic inspections and mainte-nance by correctly following the instructions inthe owner’s manual. Note that if you do notfollow these instructions, not only may theproduct break down, but the warranty will alsobe voided.Some countries have laws or regulations re-stricting users from taking the product out ofthe country where it was purchased, and itmay be impossible to register the product inthe destination country. Additionally, the war-ranty may not apply in certain regions. Whenplanning to take the product to another coun-try, consult the dealer where the product waspurchased for further information.If the product was purchased used, pleaseconsult your closest dealer for customer re-registration, and to be eligible for the specifiedservices.

NOTE:The 4ACMH, 5CMH and the standard acces-sories are used as a base for the explanationsand illustrations in this manual. Thereforesome items may not apply to every model.

EMU25120

4AC, 5COWNER’S MANUAL

©2006 by Yamaha Motor Co., Ltd.1st Edition, February 2006

All rights reserved.Any reprinting or unauthorized usewithout the written permission of

Yamaha Motor Co., Ltd.is expressly prohibited.

Printed in Japan


Table of contents

General information ..........................1Identification numbers record.......... 1

Outboard motor serial number ........... 1EC label........................................... 1GOST-R label.................................. 1Safety information ........................... 2Important labels............................... 3

Warning labels.................................... 3Fueling instructions ......................... 3

Gasoline ............................................. 4Engine oil............................................ 4

Propeller selection........................... 4Start-in-gear protection ................... 4

Basic components ............................6Main components............................ 6

Fuel tank............................................. 6Fuel tank............................................. 7Fuel joint............................................. 7Fuel gauge ......................................... 7Fuel tank cap...................................... 7Air vent screw..................................... 7Fuel cock ............................................ 7Open................................................... 8Tiller handle........................................ 8Gear shift lever ................................... 8Throttle grip ........................................ 8Throttle indicator................................. 8Throttle friction adjuster...................... 9Engine stop lanyard switch................. 9Engine stop button ........................... 10Choke knob ...................................... 10Manual starter handle....................... 10Steering friction adjuster................... 10Trim rod (tilt pin) ............................... 10Tilt support bar ................................. 11Top cowling lock lever(s)

(turn type)...................................... 11

Operation ......................................... 12Installation ..................................... 12

Mounting the outboard motor ........... 12Clamping the outboard motor........... 13

Breaking in engine ........................ 14Gasoline and engine oil mixing

chart (25:1, 50:1)........................... 14Procedure for pre-mixed models ...... 14

Preoperation checks ..................... 15Fuel .................................................. 15Oil ..................................................... 15Controls ............................................ 15Engine .............................................. 15

Filling fuel and engine oil .............. 15Filling fuel for portable tank .............. 15Filling fuel for built-in tank................. 16Gasoline and oil mixing

(50:1, 100:1).................................. 16Operating engine .......................... 18

Feeding fuel (portable tank) ............. 18Feeding fuel...................................... 19Starting engine ................................. 20

Warming up engine....................... 21Choke start models .......................... 21

Shifting .......................................... 22Forward (tiller handle and

remote control models) ................. 22Reverse ............................................ 22

Stopping engine............................ 23Procedure......................................... 23

Trimming outboard motor.............. 23Adjusting trim angle for manual

tilt models ...................................... 24Adjusting boat trim............................ 24

Tilting up and down....................... 25Procedure for tilting up

(manual tilt models)....................... 26Procedure for tilting down

(manual tilt models)....................... 27Cruising in shallow water .............. 27

Cruising in shallow water (manual tilt models)....................... 27

Cruising in other conditions........... 28


Table of contents

Maintenance..................................... 29Specifications ................................ 29Transporting and storing

outboard motor........................... 30Clamp screw mounting models ........ 30Storing outboard motor..................... 30Procedure......................................... 31Lubrication

(except oil injection models).......... 32Cleaning the outboard motor............ 32Checking painted surface of

motor............................................. 32Periodic maintenance.................... 32

Replacement parts ........................... 32Maintenance chart............................ 33Greasing........................................... 34Cleaning and adjusting spark

plug ............................................... 34Checking fuel system ....................... 35Checking fuel filter............................ 36Inspecting idling speed..................... 36Checking wiring and connectors ...... 36Exhaust leakage............................... 37Water leakage .................................. 37Checking propeller ........................... 37Removing the propeller .................... 38Installing the Propeller...................... 38Changing gear oil ............................. 38Cleaning fuel tank............................. 39Inspecting and replacing

anode(s)........................................ 40Checking top cowling ....................... 40Coating the boat bottom................... 40

Trouble Recovery............................ 42Troubleshooting ............................ 42Temporary action in

emergency ................................. 45Impact damage................................. 45Starter will not operate ..................... 45Emergency starting engine............... 46

Treatment of submerged motor..... 47Procedure......................................... 47


General information

1

EMU25170

Identification numbers recordEMU25183

Outboard motor serial numberThe outboard motor serial number is stampedon the label attached to the port side of theclamp bracket.Record your outboard motor serial number inthe spaces provided to assist you in orderingspare parts from your Yamaha dealer or forreference in case your outboard motor is sto-len.

EMU25202

EC labelEngines affixed with this label conform to cer-tain portions of the European Parliament di-rective relating to machinery. Refer to thelabel and the EC Declaration of Conformity formore details.

EMU30840

GOST-R labelEngines affixed with this label indicate confor-mity with the GOST-R certification system ofthe Russian Federation.

1. Outboard motor serial number location

1. EC label location

ZMU01696


General information

2

EMU25371

Safety information� Before mounting or operating the outboard

motor, read this entire manual. Reading itshould give you an understanding of themotor and its operation.

� Before operating the boat, read any own-er’s or operator’s manuals supplied with itand all labels. Be sure you understand eachitem before operating.

� Do not overpower the boat with this out-board motor. Overpowering the boat couldresult in loss of control. The rated power ofthe outboard should be equal to or less thanthe rated horsepower capacity of the boat.If the rated horsepower capacity of the boatis unknown, consult the dealer or boat man-ufacturer.

� Do not modify the outboard. Modificationscould make the motor unfit or unsafe to use.

� Incorrect propeller selection and incorrectuse may not only cause engine damage,but also adversely affect fuel consumption.Consult your dealer for correct use.

� Never operate after drinking alcohol or tak-ing drugs. About 50% of all boating fatalitiesinvolve intoxication.

� Have an approved personal flotation device(PFD) on board for every occupant. It is agood idea to wear a PFD whenever boat-ing. At a minimum, children and non-swim-mers should always wear PFDs, andeveryone should wear PFDs when thereare potentially hazardous boating condi-tions.

� Gasoline is highly flammable, and its va-pors are flammable and explosive. Handleand store gasoline carefully. Make surethere are no gas fumes or leaking fuel be-fore starting the engine.

� This product emits exhaust gases whichcontain carbon monoxide, a colorless,odorless gas which may cause brain dam-age or death when inhaled. Symptoms in-clude nausea, dizziness, and drowsiness.Keep cockpit and cabin areas well ventilat-ed. Avoid blocking exhaust outlets.

� Check throttle, shift, and steering for properoperation before starting the engine.

� Attach the engine stop switch lanyard to asecure place on your clothing, or your armor leg while operating. If you accidentallyleave the helm, the lanyard will pull from theswitch, stopping the engine.

� Know the marine laws and regulationswhere you will be boating - and obey them.

� Stay informed about the weather. Checkweather forecasts before boating. Avoidboating in hazardous weather.

� Tell someone where you are going: leave aFloat Plan with a responsible person. Besure to cancel the Float Plan when you re-turn.

� Use common sense and good judgmentwhen boating. Know your abilities, and besure you understand how your boat han-dles under the different boating conditionsyou may encounter. Operate within yourlimits, and the limits of your boat. Alwaysoperate at safe speeds, and keep a carefulwatch for obstacles and other traffic.

� Always watch carefully for swimmers duringthe engine operation.

� Stay away from swimming areas.� When a swimmer is in the water near you

shift into neutral and shut off the engine.� Do not illegally discard empty containers

used to replace or replenish oil. For the cor-rect processing of empty containers, con-sult the dealer where you purchased the oil.


General information

3

� When replacing oils used to lubricate theproduct (engine or gear oil), be sure to wipeaway any spilt oil. Never pour oil without us-ing a funnel or similar device. If necessary,verify the necessary replacement proce-dure with the dealer.

� Never illegally discard (dump) the product.Yamaha recommends consulting the deal-er on discarding the product.

EMU25382

Important labelsEMU25395

Warning labels

EMU25401

Label

WARNINGEWM01260

� Be sure shift control is in neutral beforestarting engine. (except 2HP)

� Do not touch or remove electrical partswhen starting or during operation.

� Keep hands, hair, and clothes away fromflywheel and other rotating parts whileengine is running.

EMU25431

Label

WARNINGEWM01300

� This engine is equipped with a neutralstarting device.

� The engine will not start unless the shiftcontrol is in neutral position.

EMU25441

Label

WARNINGEWM01311

LEAKING FUEL COULD CAUSE A FIRE.Before tilting up the engine or laying it onits side:� Turn the fuel cock to the “closed” posi-

tion.� Tighten the air-vent screw on the fuel

tank cap.

EMU25540

Fueling instructions

WARNINGEWM00010

GASOLINE AND ITS VAPORS ARE HIGH-LY FLAMMABLE AND EXPLOSIVE!� Do not smoke when refueling, and keep

away from sparks, flames, or othersources of ignition.

� Stop engine before refueling.� Refuel in a well-ventilated area. Refuel

portable fuel tanks off the boat.� Take care not to spill gasoline. If gaso-

line spills, wipe it up immediately withdry rags.

� Do not overfill the fuel tank.� Tighten the filler cap securely after refu-

eling.� If you should swallow some gasoline, in-

hale a lot of gasoline vapor, or get gaso-line in your eyes, get immediate medicalattention.

� If any gasoline spills onto your skin, im-mediately wash with soap and water.Change clothing if gasoline spills on it.

� Touch the fuel nozzle to the filler open-ing or funnel to help prevent electrostat-ic sparks.


General information

4

CAUTION:ECM00010

Use only new clean gasoline which hasbeen stored in clean containers and is notcontaminated with water or foreign matter.

EMU25590

Gasoline

If knocking or pinging occurs, use a differentbrand of gasoline or premium unleaded fuel. Ifunleaded gasoline is not available, then pre-mium gasoline can be used.EMU25650

Engine oil

If the recommended engine oil is not avail-able, another 2-stroke engine oil with anNMMA-certified TC-W3 rating may be used.EMU25742

Propeller selectionThe performance of your outboard motor willbe critically affected by your choice of propel-ler, as an incorrect choice could adversely af-fect performance and could also seriouslydamage the motor. Engine speed depends onthe propeller size and boat load. If enginespeed is too high or too low for good engineperformance, this will have an adverse effecton the engine.Yamaha outboard motors are fitted with pro-pellers chosen to perform well over a range ofapplications, but there may be uses where apropeller with a different pitch would be moreappropriate. For a greater operating load, asmaller-pitch propeller is more suitable as it

enables the correct engine speed to be main-tained. Conversely, a larger-pitch propeller ismore suitable for a smaller operating load.Yamaha dealers stock a range of propellers,and can advise you and install a propeller onyour outboard that is best suited to your appli-cation.

NOTE:Select a propeller which will allow the engineto reach the middle or upper half of the oper-ating range at full throttle with the maximumboat load. If operating conditions such as lightboat loads then allow the engine r/min to riseabove the maximum recommended range, re-duce the throttle setting to maintain the en-gine in the proper operating range.

For instructions on propeller removal and in-stallation, see page 37.EMU25760

Start-in-gear protectionYamaha outboard motors affixed with the pic-tured label or Yamaha-approved remote con-trol units are equipped with start-in-gearprotection device(s). This feature permits theengine to be started only when it is in neutral.Always select neutral before starting the en-gine.

Recommended gasoline:Regular unleaded gasoline

Recommended engine oil:YAMALUBE 2-stroke outboard motor oil

1. Propeller diameter in inches2. Propeller pitch in inches3. Type of propeller (propeller mark)

ZMU04604

-x1 2 3


General information

5

1. Start-in-gear protection label

ZMU01713

1


Basic components

6

EMU25797

Main components

NOTE:* May not be exactly as shown; also may not be included as standard equipment on all models.

EMU25802

Fuel tankIf your model was equipped with a portablefuel tank, its function is as follows.

WARNINGEWM00020

The fuel tank supplied with this engine isits dedicated fuel reservoir and must notbe used as a fuel storage container. Com-

1. Air vent screw2. Fuel tank cap3. Top cowling4. Top cowling lock lever5. Steering friction adjuster6. Anti-cavitation plate7. Propeller8. Cooling water inlet9. Trim rod10.Clamp bracket11.Clamp screw12.Tiller handle13.Throttle friction adjuster14.Manual starter handle15.Choke knob16.Engine stop button/Engine stop lanyard

switch

17.Rope attachment18.Tilt support lever19.Gear shift lever20.Fuel cock21.Fuel tank*


Basic components

7

mercial users should conform to relevantlicensing or approval authority regula-tions.

EMU25821

Fuel tankIf your model included a fuel tank, its partsand functions are as follows.

EMU25830

Fuel jointThis joint is used to connect the fuel line.EMU25841

Fuel gaugeThis gauge is located on either the fuel tankcap or on the fuel joint base. It shows the ap-proximate amount of fuel remaining in thetank.

EMU25850

Fuel tank capThis cap seals the fuel tank. When removed,the tank can be filled with fuel. To remove thecap, turn it counterclockwise.EMU25860

Air vent screwThis screw is on the fuel tank cap. To loosenthe screw, turn it counterclockwise.EMU25872

Fuel cockThe fuel cock turns on and off the supply offuel from the fuel tank to the engine.

EMU25881

CloseTo stop fuel flow to the engine, turn the leveror knob to close position.Always turn the lever or knob to close positionwhen the engine is not running.

1. Air vent screw2. Fuel gauge3. Fuel joint4. Fuel tank cap

1. Air vent screw2. Fuel tank cap

ZMU01992

3 24 1

1. Fuel cock

1. Close position


Basic components

8

EMU25901

OpenThe fuel cock has two open positions, one forselecting fuel flow from the built-in fuel tank,and one for an external tank.Fuel flows to the carburetor with the lever orknob in either open position. These are thenormal running positions.

EMU25911

Tiller handleTo change direction, move the tiller handle tothe left or right as necessary.

EMU25922

Gear shift leverPulling the gear shift lever towards you putsthe engine in forward gear so that the boatmoves ahead. Pushing the lever away fromyou puts the engine in reverse gear so that theboat moves astern.

EMU25941

Throttle gripThe throttle grip is on the tiller handle. Turnthe grip counterclockwise to increase speedand clockwise to decrease speed.

EMU25961

Throttle indicatorThe fuel consumption curve on the throttle in-dicator shows the relative amount of fuel con-sumed for each throttle position. Choose thesetting that offers the best performance andfuel economy for the desired operation.

1. “OPEN” position for the built-in tank2. “OPEN” position for the portable tank

1. Forward “ ”2. Neutral “ ”3. Reverse “ ”


Basic components

9

EMU25971

Throttle friction adjusterA friction device provides adjustable resis-tance to movement of the throttle grip or theremote control lever, and can be set accord-ing to operator preference.To increase resistance, turn the adjusterclockwise. To decrease resistance, turn theadjuster counterclockwise.

WARNINGEWM00031

Do not overtighten the friction adjuster. Ifthere is too much resistance, it could bedifficult to move the remote control leveror throttle grip, which could result in anaccident.

When constant speed is desired, tighten theadjuster to maintain the desired throttle set-ting.

EMU25990

Engine stop lanyard switchThe lock plate must be attached to the enginestop switch for the engine to run. The lanyardshould be attached to a secure place on theoperator’s clothing, or arm or leg. Should theoperator fall overboard or leave the helm, thelanyard will pull out the lock plate, stopping ig-nition to the engine. This will prevent the boatfrom running away under power.

WARNINGEWM00120

� Attach the engine stop switch lanyard toa secure place on your clothing, or yourarm or leg while operating.

� Do not attach the lanyard to clothingthat could tear loose. Do not route thelanyard where it could become entan-gled, preventing it from functioning.

� Avoid accidentally pulling the lanyardduring normal operation. Loss of enginepower means the loss of most steeringcontrol. Also, without engine power, theboat could slow rapidly. This couldcause people and objects in the boat tobe thrown forward.

NOTE:The engine cannot be started with the lockplate removed.

1. Throttle indicator

1. Lanyard2. Lock plate


Basic components

10

EMU26001

Engine stop buttonTo open the ignition circuit and stop the en-gine, push this button.

EMU26020

Choke knobTo supply the engine with the rich fuel mixturerequired to start, turn this knob to the right.

EMU26070

Manual starter handleTo start the engine, first gently pull the handleout until resistance is felt. From that position,then pull the handle straight out quickly tocrank the engine.

EMU26122

Steering friction adjusterA friction device provides adjustable resis-tance to the steering mechanism, and can beset according to operator preference. An ad-justing screw or bolt is located on the swivelbracket.

To increase resistance, turn the adjusterclockwise.To decrease resistance, turn the adjustercounterclockwise.

WARNINGEWM00040

Do not overtighten the friction adjuster. Ifthere is too much resistance, it could bedifficult to steer, which could result in anaccident.

EMU26261

Trim rod (tilt pin)The position of the trim rod determines theminimum trim angle of the outboard motor inrelation to the transom.


Basic components

11

EMU26330

Tilt support barThe tilt support bar keeps the outboard motorin the tilted up position.

EMU26372

Top cowling lock lever(s) (turn type)To remove the engine top cowling, turn thelock lever(s) and lift off the cowling. When in-stalling the cowling, check to be sure it fitsproperly in the rubber seal. Then lock thecowling again by returning the lever(s) to thelock position.

1. Top cowling lock lever(s)


Operation

12

EMU26901

Installation

CAUTION:ECM00110

Incorrect engine height or obstructions tosmooth water flow (such as the design orcondition of the boat, or accessories suchas transom ladders or depth finder trans-ducers) can create airborne water spraywhile the boat is cruising. Severe enginedamage may result if the motor is operat-ed continuously in the presence of air-borne water spray.

NOTE:During water testing check the buoyancy ofthe boat, at rest, with its maximum load.Check that the static water level on the ex-haust housing is low enough to prevent waterentry into the powerhead, when water risesdue to waves when the outboard is not run-ning.

EMU26910

Mounting the outboard motor

WARNINGEWM00820

� Overpowering a boat could cause se-vere instability. Do not install an out-board motor with more horsepower thanthe maximum rating on the capacityplate of the boat. If the boat does nothave a capacity plate, consult the boatmanufacturer.

� The information presented in this sec-tion is intended as reference only. It isnot possible to provide complete in-structions for every possible boat andmotor combination. Proper mountingdepends in part on experience and thespecific boat and motor combination.

WARNINGEWM00830

Improper mounting of the outboard motorcould result in hazardous conditions suchas poor handling, loss of control, or firehazards. Observe the following:� For permanently mounted models, your

dealer or other person experienced inproper rigging should mount the motor.If you are mounting the motor yourself,you should be trained by an experiencedperson.

� For portable models, your dealer or oth-er person experienced in proper out-board motor mounting should show youhow to mount your motor.

Mount the outboard motor on the center line(keel line) of the boat, and ensure that theboat itself is well balanced. Otherwise theboat will be hard to steer. For boats without akeel or which are asymmetrical, consult yourdealer.

EMU26920

Mounting heightTo run your boat at optimum efficiency, thewater resistance (drag) of the boat and out-board motor must be made as little as possi-ble. The mounting height of the outboardmotor greatly affects the water resistance. Ifthe mounting height is too high, cavitation

1. Center line (keel line)

ZMU017601


Operation

13

tends to occur, thus reducing the propulsion;and if the propeller tips cut the air, the enginespeed will rise abnormally and cause the en-gine to overheat. If the mounting height is toolow, the water resistance will increase andthereby reduce engine efficiency. Mount theoutboard motor so that the anti-cavitationplate is between the bottom of the boat and alevel 25 mm (1 in.) below it.

NOTE:� The optimum mounting height of the out-

board motor is affected by the boat and mo-tor combination and the desired use. Testruns at different heights can help determinethe optimum mounting height. Consult yourYamaha dealer or boat manufacturer forfurther information on determining the prop-er mounting height.

� For instructions on setting the trim angle ofthe outboard motor, see page 23.

EMU26970

Clamping the outboard motor1. Place the outboard motor on the transom

so that it is positioned as close to the cen-ter as possible. Tighten the transomclamp screws evenly and securely. Oc-casionally check the clamp screws fortightness during operation of the out-board motor because they could becomeloose due to engine vibration.

WARNINGEWM00640

Loose clamp screws could allow the out-board motor to fall off or move on the tran-som. This could cause loss of control andserious injury. Make sure the transomscrews are tightened securely. Occasion-ally check the screws for tightness duringoperation.

2. If the engine restraint cable attachment isequipped on your engine, an engine re-straint cable or chain should be used. At-tach one end to the engine restraint cableattachment and the other to a securemounting point on the boat. Otherwisethe engine could be completely lost if itaccidentally falls off the transom.

ZMU02012

ZMU02013


Operation

14

3. Secure the clamp bracket to the transomusing the bolts provided with the out-board (if packed). For details, consultyour Yamaha dealer.

WARNINGEWM00650

Avoid using bolts, nuts or washers otherthan those contained in the engine pack-aging. If used, they must be of at least thesame quality of material and strength andmust be tightened securely. After tighten-ing, test run the engine and check theirtightness.

EMU30173

Breaking in engineYour new engine requires a period of break-into allow mating surfaces of moving parts towear in evenly. Correct break-in will help en-sure proper performance and longer enginelife.

CAUTION:ECM00800

Failure to follow the break-in procedurecould result in reduced engine life or evensevere engine damage.

EMU31250

Gasoline and engine oil mixing chart (25:1, 50:1)4ACMH (25:1)

5CMH (50:1)

CAUTION:ECM00150

Be sure to mix gasoline and oil complete-ly, otherwise the engine may be damaged.

EMU27074

Procedure for pre-mixed modelsRun the engine under load (in gear with a pro-peller installed) for 10 hours as follows.1. First 10 minutes:

Run the engine at the lowest possiblespeed. A fast idle in neutral is best.

2. Next 50 minutes:Do not exceed half throttle (approximate-ly 3000 r/min). Vary engine speed occa-sionally. If you have an easy-planingboat, accelerate at full throttle onto plane,then immediately reduce the throttle to3000 r/min or less.

3. Next two hours:Accelerate at full throttle onto plane, thenreduce engine speed to three-quarterthrottle (approximately 4000 r/min). Varyengine speed occasionally. Run at fullthrottle for one minute, then allow about10 minutes of operation at three-quarterthrottle or less to let the engine cool.

4. Remaining seven hours:Run the engine at any speed. However,avoid operating at full throttle for morethan 5 minutes at a time.

1. : Gasoline2. : Engine oil



Operation

15

5. After the first 10 hours:Operate the engine normally. Use thestandard premix ratio of gasoline and oil.For details on mixing fuel and oil, seepage 15.

EMU27102

Preoperation checks

WARNINGEWM00080

If any item in the preoperation check is notworking properly, have it inspected andrepaired before operating the outboardmotor. Otherwise an accident could occur.

CAUTION:ECM00120

Do not start the engine out of water. Over-heating and serious engine damage canoccur.

EMU27111

Fuel� Check to be sure you have plenty of fuel for

your trip.� Make sure there are no fuel leaks or gaso-

line fumes.� Check fuel line connections to be sure they

are tight (if equipped Yamaha fuel tank orboat tank).

� Be sure the fuel tank is positioned on a se-cure, flat surface, and that the fuel line is nottwisted or flattened, or likely to contactsharp objects (if equipped Yamaha fueltank or boat tank).

EMU27120

Oil� Check to be sure you have plenty of oil for

your trip.EMU27130

Controls� Check throttle, shift, and steering for proper

operation before starting the engine.� The controls should work smoothly, without

binding or unusual free play.

� Look for loose or damaged connections.� Check operation of the starter and stop

switches when the outboard motor is in thewater.

EMU27140

Engine� Check the engine and engine mounting.� Look for loose or damaged fasteners.� Check the propeller for damage.EMU27233

Filling fuel and engine oilEMU27242

Filling fuel for portable tank

WARNINGEWM00060

Gasoline and its vapors are highly flam-mable and explosive. Keep away fromsparks, cigarettes, flames, or other sourc-es of ignition.

1. Remove the fuel tank cap.2. Fill the fuel tank carefully.3. Close the cap securely after refueling.

Wipe up any spilled fuel.

Fuel tank capacity (if equipped Yamaha fuel tank):

12.0 L (3.17 US gal) (2.64 Imp.gal)

ZMU04484


Operation

16

EMU27253

Filling fuel for built-in tank

WARNINGEWM00060


1. With the outboard motor tilted down (inthe vertical running position), remove thefuel tank cap.

2. Use a funnel if the nozzle on the fuel canor pump is not small enough or longenough to fit into the mouth of the fueltank.

3. Fill the fuel tank carefully.4. Securely close the cap after refueling.

Wipe up any spilled fuel.

EMU31270

Gasoline and oil mixing (50:1, 100:1)4ACMH (50:1)

5CMH (100:1)

If equipped with a portable fuel tank1. Pour oil into the portable fuel tank, and

then add gasoline.

Fuel tank capacity:2.8 L (0.74 US gal) (0.62 Imp.gal)

Gasoline to engine oil ratio

Break-in period 25:1After break-in 50:1


Gasoline to engine oil ratio

Break-in period 50:1After break-in 100:1


50:11 L

(0.26 US gal, 0.22 Imp gal)

12 L


14 L


24 L


0.02 L

(0.02 US qt, 0.02 Imp qt)

0.24 L

(0.25 US qt, 0.21 Imp qt)

0.28 L

(0.3 US qt, 0.25 Imp qt)

0.48 L

(0.51 US qt, 0.42 Imp qt)

ZMU04682

100:11 L


12 L


14 L


24 L


0.01 L

(0.01 US qt, 0.01 Imp qt)

0.12 L

(0.13 US qt, 0.11 Imp qt)

0.14 L

(0.15 US qt, 0.12 Imp qt)

0.24 L

(0.25 US qt, 0.21 Imp qt)

ZMU04910


Operation

17

2. Replace the fuel tank cap and close tight-ly.

3. Shake the fuel tank to mix the fuel thor-oughly.

4. Make sure that the oil and gasoline aremixed.

If equipped with a built-in fuel tank1. Pour oil into a clean fuel can, and then

add gasoline.

2. Replace the fuel can cap and close tight-ly.

3. Shake the fuel can to mix the fuel thor-oughly.

4. Make sure that the oil and gasoline aremixed.

5. Pour the gasoline and oil mixture into thebuilt-in fuel tank.

CAUTION:ECM00810

� Avoid using any oil other than the spec-ified type.

� Use a thoroughly blended fuel-oil mix-ture.

� If the mixture is not thoroughly mixed, orif the mixing ratio is incorrect, the fol-lowing problems could occur. Low oilratio: Lack of oil could cause major en-gine trouble, such as piston seizure.

1. Engine oil2. Gasoline

1. Engine oil2. Gasoline


Operation

18

� High oil ratio: Too much oil could causefouled spark plugs, smoky exhaust, andheavy carbon deposits.

NOTE:If using a permanently installed tank, pour theoil gradually as the gasoline is being added tothe tank.

EMU27450

Operating engineEMU27461

Feeding fuel (portable tank)

WARNINGEWM00420

� Before starting the engine, make surethat the boat is tightly moored and thatyou can steer clear of any obstructions.Be sure there are no swimmers in thewater near you.

� When the air vent screw is loosened,gasoline vapor will be released. Gaso-line is highly flammable, and its vaporsare flammable and explosive. Refrainfrom smoking, and keep away fromopen flames and sparks while looseningthe air vent screw.

� This product emits exhaust gases whichcontain carbon monoxide, a colorless,odorless gas which could cause braindamage or death when inhaled. Symp-toms include nausea, dizziness, anddrowsiness. Keep cockpit and cabin ar-eas well ventilated. Avoid blocking ex-haust outlets.

1. If there is an air vent screw on the fueltank cap, loosen it 2 or 3 turns.

2. If there is a fuel joint on the motor, firmlyconnect the fuel line to the joint. Thenfirmly connect the other end of the fuelline to the joint on the fuel tank.

3. If a steering friction adjuster is providedon your outboard motor, securely attachthe fuel line to the fuel line clamp.

ZMU02024


Operation

19

NOTE:During engine operation place the tank hori-zontally, otherwise fuel cannot be drawn fromthe fuel tank.

4. Squeeze the primer pump with the outletend up until you feel it become firm.

EMU27472

Feeding fuel

WARNINGEWM00420

� Before starting the engine, make surethat the boat is tightly moored and thatyou can steer clear of any obstructions.Be sure there are no swimmers in thewater near you.

� When the air vent screw is loosened,gasoline vapor will be released. Gaso-line is highly flammable, and its vaporsare flammable and explosive. Refrainfrom smoking, and keep away fromopen flames and sparks while looseningthe air vent screw.

� This product emits exhaust gases whichcontain carbon monoxide, a colorless,odorless gas which could cause braindamage or death when inhaled. Symp-toms include nausea, dizziness, anddrowsiness. Keep cockpit and cabin ar-eas well ventilated. Avoid blocking ex-haust outlets.

1. For the built in tank, loosen the air ventscrew on the fuel tank cap by one turn.For the external fuel tank, loosen it on thefuel tank cap by 2 or 3 turns.

2. Select the fuel tank using the fuel cock oropen the fuel cock.

3. If you are using an external fuel tank, con-nect the fuel joints securely and squeezethe primer pump with the outlet end upuntil you feel it become firm (if equippedthe fuel joint).

ZMU02025


Operation

20

EMU27490

Starting engineEMU27505

Manual start models (tiller control)1. Place the gear shift lever in neutral.

NOTE:The start-in-gear protection device preventsthe engine from starting except when in neu-tral.

2. Attach the engine stop switch lanyard toa secure place on your clothing, or yourarm or leg. Then install the lock plate onthe other end of the lanyard into the en-gine stop switch.

WARNINGEWM00120

� Attach the engine stop switch lanyard toa secure place on your clothing, or yourarm or leg while operating.

� Do not attach the lanyard to clothingthat could tear loose. Do not route thelanyard where it could become entan-gled, preventing it from functioning.


3. Place the throttle grip in the “ ”(start) position.

4. Pull out / turn the choke knob fully. Afterthe engine starts, replace / return theknob to the home position.

NOTE:� It is not necessary to use the choke when

starting a warm engine.


Operation

21

� If the choke knob is left in the “ ” (start)position while the engine is running, the en-gine will run poorly or stall.

5. Pull the manual starter handle slowly untilyou feel resistance. Then give a strongpull straight out to crank and start the en-gine. Repeat if necessary.

6. After the engine starts, slowly return themanual starter handle to its original posi-tion before releasing it.

7. Slowly return the throttle grip to the fullyclosed position.

NOTE:� When the engine is cold, it needs to be

warmed up. For further information, seepage 21.

� If the engine does not start on the first try,repeat the procedure. If the engine fails tostart after 4 or 5 tries, open the throttle asmall amount (between 1/8 and 1/4) and try

again. Also if the engine is warm and fails tostart, open the throttle a same amount andtry to start the engine again. If the enginestill fails to start, see page 42.

EMU27670

Warming up engineEMU27681

Choke start models1. After starting the engine, allow it to idle for

3 minutes to warm up. Failure to do so willshorten engine life. Gradually return thechoke knob to its home position as theengine warms up.

2. Check for a steady flow of water from thecooling water pilot hole.

CAUTION:ECM00511

A continuous flow of water from the cool-ing water pilot hole shows that the waterpump is pumping water through the cool-ing passages. If water is not flowing out ofthe hole at all times while the engine isrunning, overheating and serious damagecould occur. Stop the engine and checkwhether the cooling water inlet on the low-er case or the cooling water pilot hole isblocked. Consult your Yamaha dealer ifthe problem cannot be located and cor-rected.

ZMU02030


Operation

22

EMU27740

Shifting

WARNINGEWM00180

Before shifting, make sure there are noswimmers or obstacles in the water nearyou.

CAUTION:ECM00220

To change the boat direction or shiftingposition from forward to reverse or vice-versa, first close the throttle so that the en-gine idles (or runs at low speeds).

EMU27764

Forward (tiller handle and remote con-trol models)Tiller handle models1. Place the throttle grip in the fully closed

position.

2. Move the gear shift lever quickly and firm-ly from neutral to forward.

Remote control modelsPull up the neutral interlock trigger (ifequipped) and move the remote control leverquickly and firmly from neutral to forward.EMU27801

Reverse

WARNINGEWM00190

When operating in reverse, go slowly. Donot open the throttle more than half. Other-wise the boat could become unstable,which could result in loss of control andan accident.

1. Place the throttle grip in the fully closedposition.

2. Move the gear shift lever quickly and firm-ly from neutral to reverse.

ZMU02030


Operation

23

NOTE:The outboard motor can turn 360° in its brack-et (full-pivot system). The boat can also bebacked up by simply turning the outboard mo-tor around 180° with the steering handle fac-ing toward you.

EMU27820

Stopping engineBefore stopping the engine, first let it cool offfor a few minutes at idle or low speed. Stop-ping the engine immediately after operating athigh speed is not recommended.EMU27832

Procedure1. Push and hold the engine stop button un-

til the engine comes to a complete stop.

2. After stopping the engine, tighten the airvent screw on the fuel tank cap and setthe fuel cock lever or knob to the closedposition, if equipped.

3. Disconnect the fuel line if you are usingan external fuel tank.

NOTE:If the outboard motor is equipped with an en-gine stop switch lanyard, the engine can alsobe stopped by pulling the lanyard and remov-ing the lock plate from the engine stop switch.

EMU27861

Trimming outboard motorThe trim angle of the outboard motor helpsdetermine the position of the bow of the boatin the water. Correct trim angle will help im-prove performance and fuel economy whilereducing strain on the engine. Correct trim an-gle depends upon the combination of boat,engine, and propeller. Correct trim is also af-fected by variables such as the load in theboat, sea conditions, and running speed.

WARNINGEWM00740

Excessive trim for the operating condi-tions (either trim up or trim down) cancause boat instability and can make steer-ing the boat more difficult. This increasesthe possibility of an accident. If the boatbegins to feel unstable or is hard to steer,slow down and/or readjust the trim angle.


Operation

24

EMU27872

Adjusting trim angle for manual tilt modelsThere are 4 or 5 holes provided in the clampbracket to adjust the outboard motor trim an-gle.1. Stop the engine.2. Tilt the outboard motor up, and then re-

move the trim rod from the clamp bracket.

3. Reposition the rod in the desired hole.To raise the bow (“trim-out”), move the rodaway from the transom.To lower the bow (“trim-in”), move the rod to-ward the transom.Make test runs with the trim set to different an-gles to find the position that works best foryour boat and operating conditions.

WARNINGEWM00400

� Stop the engine before adjusting thetrim angle.

� Use care to avoid being pinched whenremoving or installing the rod.

� Use caution when trying a trim positionfor the first time. Increase speed gradu-ally and watch for any signs of instabilityor control problems. Improper trim an-gle can cause loss of control.

NOTE:The outboard motor trim angle can bechanged approximately 4 degrees by shiftingthe trim rod one hole.

EMU27911

Adjusting boat trimWhen the boat is on plane, a bow-up attituderesults in less drag, greater stability and effi-ciency. This is generally when the keel line ofthe boat is up about 3 to 5 degrees. With thebow up, the boat may have a greater tenden-cy to steer to one side or the other. Compen-sate for this as you steer. The trim tab canalso be adjusted to help offset this effect.When the bow of the boat is down, it is easierto accelerate from a standing start onto plane.

1. Trim operating angle

1. Trim rod


Operation

25

Bow UpToo much trim-out puts the bow of the boattoo high in the water. Performance and econ-omy are decreased because the hull of theboat is pushing the water and there is more airdrag. Excessive trim-out can also cause thepropeller to ventilate, which reduces perfor-mance further, and the boat may “porpoise”(hop in the water), which could throw the op-erator and passengers overboard.

Bow DownToo much trim-in causes the boat to “plow”through the water, decreasing fuel economyand making it hard to increase speed. Operat-ing with excessive trim-in at higher speedsalso makes the boat unstable. Resistance atthe bow is greatly increased, heightening thedanger of “bow steering” and making opera-tion difficult and dangerous.

NOTE:Depending on the type of boat, the outboardmotor trim angle may have little effect on thetrim of the boat when operating.

EMU27921

Tilting up and downIf the engine will be stopped for some time orif the boat is moored in shallows, the outboardmotor should be tilted up to protect the propel-ler and casing from damage by collision withobstructions, and also to reduce salt corro-sion.

WARNINGEWM00220

Be sure all people are clear of the out-board motor when tilting up and down,also be careful not to pinch any body partsbetween the drive unit and engine bracket.

WARNINGEWM00230

Leaking fuel is a fire hazard. Tighten theair vent screw and place the fuel cock inthe closed position if the outboard motorwill be tilted for more than a few minutes.Otherwise fuel may leak.

CAUTION:ECM00231

� Before tilting the outboard motor, followthe procedure under “Stopping engine”in this chapter. Never tilt the outboardmotor while the engine is running. Se-vere damage from overheating can re-sult.

� Do not tilt up the engine by pushing thetiller handle because this could breakthe handle.

� Keep the power unit higher than the pro-peller at all times. Otherwise water couldrun into the cylinder and cause damage.


Operation

26

� The outboard motor cannot be tiltedwhen in reverse or when the outboardmotor is turned 180° (facing the rear).

EMU27964

Procedure for tilting up (manual tilt models)1. Place the gear shift lever in neutral (if

equipped) and face the outboard motorforward.

2. On full-pivot system models, tighten thesteering friction adjuster by turning itclockwise to prevent the motor from turn-ing freely.

3. Tighten the air vent screw. On modelsequipped with a fuel joint, disconnect thefuel line from the outboard motor.

4. Close the fuel cock.

5. Tilt support bar equipped models: Holdthe rear of the top cowling or the rear han-dle (if equipped) with one hand and tilt theoutboard motor up fully until the tilt sup-port bar automatically locks.

6. Tilt support knob equipped models: Holdthe rear of the top cowling with one hand,fully tilt the outboard motor up, and pushthe tilt support knob into the clamp brack-et.


Operation

27

7. Tilt support lever equipped models: Holdthe rear handle and tilt the engine up fullyuntil the tilt support lever automaticallylocks.

NOTE:Tilt support lever/bar equipped models: If themotor is not facing forward, the tilt support le-ver/bar cannot automatically turn to thelocked position. If the tilt support lever/bardoes not automatically lock, swing the motora little to the left and right.

EMU28032

Procedure for tilting down (manual tilt models)1. Slightly tilt the outboard motor up.2. If equipped with the tilt support bar: Slow-

ly tilt the outboard motor down while pull-ing the tilt support bar lever up.

3. If equipped with the tilt support knob: Pullthe knob out, and then slowly tilt the out-board motor down.

4. If equipped with the tilt support lever:Slowly tilt the outboard motor down whilepulling the tilt support lever up.

5. Loosen the steering friction adjuster byturning it counterclockwise, and adjustthe steering friction according to operatorpreference.

WARNINGEWM00720

If there is too much resistance it could bedifficult to steer, which could result in anaccident.

EMU28060

Cruising in shallow waterThe outboard motor can be tilted up partiallyto allow operation in shallow water.EMU28071

Cruising in shallow water (manual tilt models)

WARNINGEWM00710

� Place the gear shift in neutral before us-ing the shallow water cruising system.

� Run the boat at the lowest possiblespeed when using the shallow watercruising system. The tilt lock mecha-nism does not work while the shallowwater cruising system is being used. Hit-ting an underwater obstacle couldcause the outboard motor to lift out ofthe water, resulting in loss of control.

� Do not rotate the outboard motor 180°and operate the boat in reverse. Placethe gear shift in reverse to operate theboat in reverse.

� Use extra care when operating in re-verse. Too much reverse thrust cancause the outboard motor to lift out ofthe water, increasing the chance of acci-dent and personal injury.

� Return the outboard motor to its normalposition as soon as the boat is back indeeper water.

CAUTION:ECM00260

Do not tilt the outboard motor up so thatthe cooling water inlet on the lower unit isabove the surface of the water when set-


Operation

28

ting up for and cruising in shallow water.Otherwise severe damage from overheat-ing can result.

EMU28101

Procedure1. Place the gear shift lever in neutral and

face the outboard motor forward.

2. Slightly tilt the outboard motor up until thetilt support bar automatically turns to thelock position to support the engine.

3. To lower the outboard motor to the nor-mal running position, first slightly tilt theoutboard motor up. Then pull up the tiltsupport bar lever and slowly tilt the en-gine down.

NOTE:The outboard motor is equipped with 2 or 3positions for shallow water cruising.

EMU28192

Cruising in other conditionsCruising in salt waterAfter operating in salt water, flush the coolingwater passages with fresh water to preventthem from becoming clogged with salt depos-its.

NOTE:For cooling system flushing instructions, seepage 30.

Cruising in turbid waterYamaha strongly recommends that you usethe optional chromium-plated water pump kit(not available for some models) if you use theoutboard motor in turbid or muddy water con-ditions.


Maintenance

29

EMU31480

Specifications

NOTE:“(AL)” stated in the specification data belowrepresents the numerical value for the alumi-num propeller installed.Likewise, “(SUS)” represents the value forstainless steel propeller installed and “(PL)”for plastic propeller installed.

EMU28218

Dimension:Overall length:

677 mm (26.7 in)Overall width:

322 mm (12.7 in)Overall height S:

1011 mm (39.8 in)Overall height L:

1138 mm (44.8 in)Transom height S:

444 mm (17.5 in)Transom height L:

571 mm (22.5 in)Weight (AL) S:

21.0 kg (46 lb)Weight (AL) L:

21.5 kg (47 lb)Performance:

Full throttle operating range:4500–5500 r/min

Maximum output:4ACMH 2.9 kW@5000 r/min (4 HP@5000 r/min)5CMH 3.7 kW@5000 r/min (5 HP@5000 r/min)

Idling speed (in neutral):1150 ±50 r/min

Engine:Type:

2-stroke SDisplacement:

4ACMH 83.0 cm³ (5.06 cu.in)5CMH 103.0 cm³ (6.29 cu.in)

Bore × stroke:4ACMH 50.0 × 42.0 mm (1.97 × 1.65 in)5CMH 54.0 × 45.0 mm (2.13 × 1.77 in)

Ignition system:CDI

Spark plug (NGK):4ACMH B7HS5CMH BR7HS

Spark plug gap:0.6–0.7 mm (0.024–0.028 in)

Control system:Tiller

Starting system:Manual

Starting carburetion system:Choke valve

Alternator output:40/60 W

Drive unit:Gear positions:

Forward-neutral-reverseGear ratio:

2.08 (27/13)Trim and tilt system:

Manual tiltPropeller mark:

BAFuel and oil:

Recommended fuel:Regular unleaded gasoline

Fuel tank capacity:12.0 L (3.17 US gal) (2.64 Imp.gal)

Fuel tank capacity (built in type):2.8 L (0.74 US gal) (0.62 Imp.gal)

Recommended engine oil:YAMALUBE 2-stroke outboard motor oil

Fuel:oil ratio:Regular gasoline:

4ACMH 50 :15CMH 100 :1

Lubrication:Pre-mixed fuel and oil

Recommended gear oil:Hypoid gear oil SAE#90

Gear oil quantity:100.0 cm³ (3.38 US oz) (3.53 Imp.oz)

Tightening torque for engine:Spark plug:

25.0 Nm (18.4 ft-lb) (2.55 kgf-m)


Maintenance

30

EMU28222

Transporting and storing out-board motor

WARNINGEWM00690

� Leaking fuel is a fire hazard. When trans-porting and storing the outboard motor,close the air vent screw and fuel cock toprevent fuel from leaking.

� USE CARE when transporting fuel tank,whether in a boat or car.

� DO NOT fill fuel container to maximumcapacity. Gasoline will expand consider-ably as it warms up and can build uppressure in the fuel container. This cancause fuel leakage and a potential firehazard.

WARNINGEWM00700

Never get under the lower unit while it istilted, even if a motor support bar is used.Severe injury could occur if the outboardmotor accidentally falls.

CAUTION:ECM00660

Do not use the tilt support lever or knobwhen trailering the boat. The outboard mo-tor could shake loose from the tilt supportand fall. If the motor cannot be trailered inthe normal running position, use an addi-tional support device to secure it in the tiltposition.

The outboard motor should be trailered andstored in the normal running position. If thereis insufficient road clearance in this position,then trailer the outboard motor in the tilt posi-tion using a motor support device such as atransom saver bar. Consult your Yamahadealer for further details.

EMU28235

Clamp screw mounting modelsWhen transporting or storing the outboardmotor while removed from a boat, keep theoutboard motor in the attitude shown.

NOTE:Place a towel or something similar under theoutboard motor to protect it from damage.

EMU30272

Storing outboard motorWhen storing your Yamaha outboard motorfor prolonged periods of time (2 months orlonger), several important procedures mustbe performed to prevent excessive damage.It is advisable to have your outboard motorserviced by an authorized Yamaha dealer pri-or to storage. However, you, the owner, with aminimum of tools, can perform the followingprocedures.


Maintenance

31

CAUTION:ECM01411

� Do not place the outboard motor on itsside before the cooling water hasdrained from it completely, otherwisewater may enter the cylinder through theexhaust port and cause engine trouble.

� Store the outboard motor in a dry, well-ventilated place, not in direct sunlight.

EMU28302

ProcedureEMU28313

Flushing in a water tank1. Wash the outboard motor body using

fresh water. For further information, seepage 32.

2. Place the fuel cock in the closed positionand disconnect the fuel line if equipped.Tighten the air vent screw, if equipped.

3. Remove the engine top cowling and si-lencer cover.

4. Install the outboard motor on the testtank.

5. Fill the tank with fresh water to above thelevel of the anti-cavitation plate.

CAUTION:ECM00290

If the fresh water level is below the level ofthe anti-cavitation plate, or if the watersupply is insufficient, engine seizure mayoccur.

6. Cooling system flushing is essential toprevent the cooling system from cloggingup with salt, sand, or dirt. In addition, fog-ging/lubricating of the engine is mandato-ry to prevent excessive engine damagedue to rust. Perform the flushing and fog-ging at the same time.

WARNINGEWM00090


� Keep hands, hair, and clothes away fromthe flywheel and other rotating partswhile the engine is running.

7. Run the engine at a fast idle for a fewminutes in neutral position.

8. Just prior to turning off the engine, quicklyspray “Fogging Oil” alternately into eachcarburetor or the fogging hole of the si-lencer cover, if equipped. When properlydone, the engine will smoke excessivelyand almost stall.

9. If “Fogging Oil” is not available, run theengine at a fast idle until the fuel systemempties and the engine stops.

10. Remove the outboard motor from the testtank.

11. Install the silencer cover or fogging holecap, and the top cowling.

12. Drain the cooling water completely out ofthe motor. Clean the body thoroughly.

1. Lowest water level2. Water surface

ZMU02704

2

1


Maintenance

32

13. If “Fogging Oil” is not available, removethe spark plug(s). Pour a teaspoonful ofclean engine oil into each cylinder. Crankseveral times manually. Replace thespark plug(s).

14. Drain the fuel from both the built-in andportable fuel tanks, on equipped models.

NOTE:Portable fuel tank equipped models: Store theportable fuel tank in a dry, well-ventilatedplace, not in direct sunlight.

EMU28400

Lubrication (except oil injection mod-els)1. Grease the spark plug threads and install

the spark plug(s) and torque to properspecification. For information on sparkplug installation, see page 34.

2. Change the gear oil. For instructions, seepage 38. Inspect the oil for the presenceof water that indicates a leaky seal. Sealreplacement should be performed by anauthorized Yamaha dealer prior to use.

3. Grease all grease fittings. For further de-tails, see page 34.

EMU28450

Cleaning the outboard motorAfter use, wash the exterior of the outboardmotor with fresh water. Flush the cooling sys-tem with fresh water.

NOTE:For cooling system flushing instructions, seepage 30.

EMU28460

Checking painted surface of motorCheck the motor for scratches, nicks, or flak-ing paint. Areas with damaged paint are morelikely to corrode. If necessary, clean and paintthe areas. A touch-up paint is available fromyour Yamaha dealer.EMU28476

Periodic maintenance

WARNINGEWM01070

Be sure to turn off the engine when youperform maintenance unless otherwisespecified. If you or the owner is not famil-iar with machine servicing, this workshould be done by your Yamaha dealer orother qualified mechanic.

EMU28510

Replacement partsIf replacement parts are necessary, use onlygenuine Yamaha parts or parts of the sametype and of equivalent strength and materials.Any part of inferior quality may malfunction,and the resulting loss of control could endan-ger the operator and passengers. Yamahagenuine parts and accessories are availablefrom your Yamaha dealer.


Maintenance

33

EMU28522

Maintenance chartFrequency of maintenance operations may be adjusted according to the operating conditions,but the following table gives general guidelines. Refer to the sections in this chapter for expla-nations of each owner-specific action.

NOTE:When operating in salt water, turbid or muddy water, the engine should be flushed with cleanwater after each use.

The “ ” symbol indicates the check-ups which you may carry out yourself.The “ ” symbol indicates work to be carried out by your Yamaha dealer.

Item Actions

Initial Every

10 hours (1 month)

50 hours (3 months)

100 hours (6 months)

200 hours (1 year)

Anode(s) (external) Inspection / replace-ment

Cooling water passag-es Cleaning

Cowling clamp Inspection

Fuel filter (disposable) Inspection / replace-ment

Fuel filter (inside built-in fuel tank) Inspection / cleaning

Fuel system Inspection

Fuel tank (built-in tank) Inspection / cleaning

Fuel tank (Yamaha por-table tank) Inspection / cleaning

Gear oil Change

Greasing points Greasing

Idling speed (carbure-tor models) Inspection

Propeller and cotter pin Inspection / replace-ment

Shift link / shift cable Inspection / adjustment

Thermostat Inspection / replace-ment

Throttle link / throttle cable / throttle pick-up timing

Inspection / adjustment

Water pump Inspection / replace-ment

Spark plug(s) Cleaning / adjustment / replacement


Maintenance

34

EMU28940

GreasingYamaha grease A (water resistant grease)Yamaha grease D (corrosion resistant grease; for propeller shaft)

EMU28952

Cleaning and adjusting spark plug

WARNINGEWM00560

When removing or installing a spark plug,be careful not to damage the insulator. Adamaged insulator could allow externalsparks, which could lead to explosion orfire.

The spark plug is an important engine compo-nent and is easy to inspect. The condition ofthe spark plug can indicate something aboutthe condition of the engine. For example, if thecenter electrode porcelain is very white, thiscould indicate an intake air leak or carburetionproblem in that cylinder. Do not attempt to di-agnose any problems yourself. Instead, takethe outboard motor to a Yamaha dealer. You


Maintenance

35

should periodically remove and inspect thespark plug because heat and deposits willcause the spark plug to slowly break downand erode. If electrode erosion becomes ex-cessive, or if carbon and other deposits areexcessive, you should replace the spark plugwith another of the correct type.

Before fitting the spark plug, measure theelectrode gap with a wire thickness gauge;adjust the gap to specification if necessary.

When fitting the plug, always clean the gasketsurface and use a new gasket. Wipe off anydirt from the threads and screw in the sparkplug to the correct torque.

NOTE:If a torque-wrench is not available when youare fitting a spark plug, a good estimate of thecorrect torque is 1/4 to 1/2 a turn past finger-

tight. Have the spark plug adjusted to the cor-rect torque as soon as possible with a torque-wrench.

EMU28962

Checking fuel system

WARNINGEWM00060


WARNINGEWM00910

Leaking fuel can result in fire or explosion.� Check for fuel leakage regularly.� If any fuel leakage is found, the fuel sys-

tem must be repaired by a qualified me-chanic. Improper repairs can make theoutboard unsafe to operate.

Check the fuel lines for leaks, crack, or mal-function. If a problem is found, your Yamahadealer or other qualified mechanic should re-pair it immediately.

Standard spark plug:4ACMH B7HS5CMH BR7HS

1. Spark plug gap2. Spark plug I.D. mark (NGK)

Spark plug gap:0.6–0.7 mm (0.024–0.028 in)

Spark plug torque:25.0 Nm (18.4 ft-lb) (2.55 kgf-m)


Maintenance

36

Checkpoints� Fuel system parts leakage� Fuel line joint leakage� Fuel line cracks or other damage� Fuel connector leakageEMU28990

Checking fuel filterCheck the fuel filter periodically. The fuel filteris a one piece, disposable type. If foreign mat-ter is found in the filter, replace it. For replace-ment of the fuel filter, consult your Yamahadealer.

EMU29041

Inspecting idling speed

WARNINGEWM00451


� Keep hands, hair, and clothes away fromthe flywheel and other rotating partswhile the engine is running.

CAUTION:ECM00490

This procedure must be performed whilethe outboard motor is in the water. A flush-ing attachment or test tank can be used.

A diagnostic tachometer should be used forthis procedure. Results may vary dependingon whether testing is conducted with theflushing attachment, in a test tank, or with theoutboard motor in the water.1. Start the engine and allow it to warm up

fully in neutral until it is running smoothly.

NOTE:Correct idling speed inspection is only possi-ble if the engine is fully warmed up. If notwarmed up fully, the idle speed will measurehigher than normal. If you have difficulty veri-fying the idle speed, or the idle speed requiresadjustment, consult a Yamaha dealer or otherqualified mechanic.

2. Verify whether the idle speed is set tospecification. For idle speed specifica-tions, see page 29.

EMU29112

Checking wiring and connectors� Check that each grounding wire is properly

secured.� Check that each connector is engaged se-

curely.


Maintenance

37

EMU29120

Exhaust leakageStart the engine and check that no exhaustleaks from the joints between the exhaustcover, cylinder head, and body cylinder.EMU29130

Water leakageStart the engine and check that no waterleaks from the joints between the exhaustcover, cylinder head, and body cylinder.EMU29171

Checking propeller

WARNINGEWM00321

You could be seriously injured if the en-gine accidentally starts when you are nearthe propeller.� Before inspecting, removing, or install-

ing the propeller, remove the spark plugcaps from the spark plugs. Also, placethe shift control in neutral, turn the mainswitch to “ ” (off) and remove the key,and remove the lanyard from the enginestop switch. Turn off the battery cut-offswitch if your boat has one.

� Do not use your hand to hold the propel-ler when loosening or tightening thepropeller nut. Put a wood block betweenthe anti-cavitation plate and the propel-ler to prevent the propeller from turning.

Checkpoints� Check each of the propeller blades for

wear, erosion from cavitation or ventilation,or other damage.

� Check the propeller shaft for damage.� Check the splines / shear pin for wear or

damage.� Check for fish line tangled around the pro-

peller shaft.

� Check the propeller shaft oil seal for dam-age.

NOTE:If the shear pin equipped: it is designed tobreak if the propeller hits a hard underwaterobstacle to help protect the propeller anddrive mechanism. The propeller will then spinfreely on the shaft. If this happens, the shearpin must be replaced.ZMU01896


Maintenance

38

EMU30660

Removing the propellerEMU29194

Spline models1. Straighten the cotter pin and pull it out us-

ing a pair of pliers.2. Remove the propeller nut, washer, and

spacer (if equipped).

3. Remove the propeller and thrust washer.EMU30670

Installing the PropellerEMU30371

Spline models

CAUTION:ECM00340

� Be sure to install the thrust washer be-fore installing the propeller, otherwisethe lower case and propeller boss couldbe damaged.

� Be sure to use a new cotter pin and bendthe ends over securely. Otherwise thepropeller could come off during opera-tion and be lost.

1. Apply Yamaha marine grease or a corro-sion resistant grease to the propellershaft.

2. Install the spacer (if equipped), thrustwasher, and propeller on the propellershaft.

3. Install the spacer (if equipped) and thewasher. Tighten the propeller nut untilthere is no forward-and-backward move-ment.

4. Align the propeller nut with the propellershaft hole. Insert a new cotter pin in thehole and bend the cotter pin ends.

NOTE:If the propeller nut does not align with the pro-peller shaft hole after tightening it, loosen thenut until it aligns with the hole.

EMU29282

Changing gear oil

WARNINGEWM00800

� Be sure the outboard motor is securelyfastened to the transom or a stablestand. You could be severely injured ifthe outboard motor falls on you.

� Never get under the lower unit while it istilted, even when the tilt support lever orknob is locked. Severe injury could oc-cur if the outboard motor accidentallyfalls.

1. Tilt the outboard motor so that the gear oildrain screw is at the lowest point possi-ble.

1. Cotter pin2. Propeller nut3. Washer4. Propeller5. Thrust washer


Maintenance

39

2. Place a suitable container under the gearcase.

3. Remove the gear oil drain screw and gas-ket.

NOTE:� If a magnetic gear oil drain screw is

equipped, remove all metal particles fromthe screw before installing it.

� Always use new gaskets. Do not reuse theremoved gaskets.

4. Remove the oil level plug and gasket toallow the oil to drain completely.

CAUTION:ECM00710

Inspect the used oil after it has beendrained. If the oil is milky, water is gettinginto the gear case which can cause geardamage. Consult a Yamaha dealer for re-pair of the lower unit seals.

NOTE:For disposal of used oil, consult your Yamahadealer.

5. With the outboard motor in a vertical po-sition, and using a flexible or pressurizedfilling device, inject the gear oil into thegear oil drain screw hole.

6. Put a new gasket on the oil level plug.When the oil begins to flow out of the oillevel plug hole, insert and tighten the oillevel plug.

7. Put a new gasket on the gear oil drainscrew. Insert and tighten the gear oildrain screw.

EMU29302

Cleaning fuel tank

WARNINGEWM00920

Gasoline is highly flammable, and its va-pors are flammable and explosive.� If you have any question about properly

doing this procedure, consult yourYamaha dealer.

� Keep away from sparks, cigarettes,flames, or other sources of ignitionwhen cleaning the fuel tank.

� Remove the fuel tank from the boat be-fore cleaning it. Work only outdoors inan area with good ventilation.

� Wipe up any spilled fuel immediately.� Reassemble the fuel tank carefully. Im-

proper assembly can result in a fuelleak, which could result in a fire or ex-plosion hazard.

1. Gear oil drain screw2. Oil level plug

Recommended gear oil:Hypoid gear oil SAE#90

Gear oil quantity:100.0 cm³ (3.38 US oz) (3.53 Imp.oz)


Maintenance

40

� Dispose of old gasoline according to lo-cal regulations.

1. Empty the fuel tank into an approved con-tainer.

2. Pour a small amount of suitable solventinto the tank. Install the cap and shakethe tank. Drain the solvent completely.

3. Remove the screws holding the fuel jointassembly. Pull the assembly out of thetank.

4. Clean the filter (located on the end of thesuction pipe) in a suitable cleaning sol-vent. Allow the filter to dry.

5. Replace the gasket with a new one. Re-install the fuel joint assembly and tightenthe screws firmly.

EMU29312

Inspecting and replacing anode(s)Yamaha outboard motors are protected fromcorrosion by sacrificial anodes. Inspect theexternal anodes periodically. Remove scalesfrom the surfaces of the anodes. Consult aYamaha dealer for replacement of externalanodes.

CAUTION:ECM00720

Do not paint anodes, as this would renderthem ineffective.

NOTE:Inspect ground leads attached to external an-odes on equipped models. Consult a Yamahadealer for inspection and replacement of inter-nal anodes attached to the power unit.

EMU29390

Checking top cowlingCheck the fitting of the top cowling by pushingit with both hands. If it is loose have it repairedby your Yamaha dealer.

EMU29400

Coating the boat bottomA clean hull improves boat performance. Theboat bottom should be kept as clean of marinegrowth as possible. If necessary, the boat bot-tom can be coated with an anti-fouling paintapproved for your area to inhibit marinegrowth.Do not use anti-fouling paint which includescopper or graphite. These paints can causemore rapid engine corrosion.


Maintenance

41


Trouble Recovery

42

EMU29424

TroubleshootingA problem in the fuel, compression, or ignitionsystems can cause poor starting, loss of pow-er, or other problems. This section describesbasic checks and possible remedies, and cov-ers all Yamaha outboard motors. Thereforesome items may not apply to your model.If your outboard motor requires repair, bring itto your Yamaha dealer.If the engine trouble warning indicator is flash-ing, consult your Yamaha dealer.

Starter will not operate.Q. Is battery capacity weak or low?A. Check battery condition. Use battery of rec-ommended capacity.

Q. Are battery connections loose or corrod-ed?A. Tighten battery cables and clean batteryterminals.

Q. Is fuse for electric start relay or electric cir-cuit blown?A. Check for cause of electric overload andrepair. Replace fuse with one of correct am-perage.

Q. Are starter components faulty?A. Have serviced by a Yamaha dealer.

Q. Is shift lever in gear?A. Shift to neutral.

Engine will not start (starter operates).Q. Is fuel tank empty?A. Fill tank with clean, fresh fuel.

Q. Is fuel contaminated or stale?A. Fill tank with clean, fresh fuel.

Q. Is fuel filter clogged?A. Clean or replace filter.

Q. Is starting procedure incorrect?A. See page 20.

Q. Has fuel pump malfunctioned?A. Have serviced by a Yamaha dealer.

Q. Are spark plug(s) fouled or of incorrecttype?A. Inspect spark plug(s). Clean or replace withrecommended type.

Q. Are spark plug cap(s) fitted incorrectly?A. Check and re-fit cap(s).

Q. Is ignition wiring damaged or poorly con-nected?A. Check wires for wear or breaks. Tighten allloose connections. Replace worn or brokenwires.

Q. Are ignition parts faulty?A. Have serviced by a Yamaha dealer.

Q. Is engine stop switch lanyard not at-tached?A. Attach lanyard.

Q. Are engine inner parts damaged?A. Have serviced by a Yamaha dealer.

Engine idles irregularly or stalls.Q. Are spark plug(s) fouled or of incorrecttype?A. Inspect spark plug(s). Clean or replace withrecommended type.

Q. Is fuel system obstructed?


Trouble Recovery

43

A. Check for pinched or kinked fuel line or oth-er obstructions in fuel system.



Q. Have ignition parts failed?A. Have serviced by a Yamaha dealer.

Q. Has warning system activated?A. Find and correct cause of warning.

Q. Is spark plug gap incorrect?A. Inspect and adjust as specified.


Q. Is specified engine oil not being used?A. Check and replace oil as specified.

Q. Is thermostat faulty or clogged?A. Have serviced by a Yamaha dealer.

Q. Are carburetor adjustments incorrect?A. Have serviced by a Yamaha dealer.

Q. Is fuel pump damaged?A. Have serviced by a Yamaha dealer.

Q. Is air vent screw on fuel tank closed?A. Open air vent screw.

Q. Is choke knob pulled out?

A. Return to home position.

Q. Is motor angle too high?A. Return to normal operating position.

Q. Is carburetor clogged?A. Have serviced by a Yamaha dealer.

Q. Is fuel joint connection incorrect?A. Connect correctly.

Q. Is throttle valve adjustment incorrect?A. Have serviced by a Yamaha dealer.

Q. Is battery cable disconnected?A. Connect securely.

Warning buzzer sounds or indicator lights.Q. Is cooling system clogged?A. Check water intake for restriction.

Q. Is engine oil level low?A. Fill oil tank with specified engine oil.

Q. Is heat range of spark plug incorrect?A. Inspect spark plug and replace it with rec-ommended type.

Q. Is specified engine oil not being used?A. Check and replace oil with specified type.

Q. Is engine oil contaminated or deteriorated?A. Replace oil with fresh, specified type.

Q. Is oil filter clogged?A. Have serviced by a Yamaha dealer.

Q. Has oil feed/injection pump malfunc-tioned?A. Have serviced by a Yamaha dealer.


Trouble Recovery

44

Q. Is load on boat improperly distributed?A. Distribute load to place boat on an evenplane.

Q. Is water pump or thermostat faulty?A. Have serviced by a Yamaha dealer.

Q. Is there excess water in fuel filter cup?A. Drain filter cup.

Engine power loss.Q. Is propeller damaged?A. Have propeller repaired or replaced.

Q. Is propeller pitch or diameter incorrect?A. Install correct propeller to operate outboardat its recommended speed (r/min) range.

Q. Is trim angle incorrect?A. Adjust trim angle to achieve most efficientoperation.

Q. Is motor mounted at incorrect height ontransom?A. Have motor adjusted to proper transomheight.

Q. Has warning system activated?A. Find and correct cause of warning.

Q. Is boat bottom fouled with marine growth?A. Clean boat bottom.

Q. Are spark plug(s) fouled or of incorrecttype?A. Inspect spark plug(s). Clean or replace withrecommended type.

Q. Are weeds or other foreign matter tangledon gear housing?

A. Remove foreign matter and clean lowerunit.

Q. Is fuel system obstructed?A. Check for pinched or kinked fuel line or oth-er obstructions in fuel system.



Q. Is spark plug gap incorrect?A. Inspect and adjust as specified.


Q. Have electrical parts failed?A. Have serviced by a Yamaha dealer.

Q. Is specified fuel not being used?A. Replace fuel with specified type.

Q. Is specified engine oil not being used?A. Check and replace oil with specified type.

Q. Is thermostat faulty or clogged?A. Have serviced by a Yamaha dealer.

Q. Is air vent screw closed?A. Open the air vent screw.

Q. Is fuel pump damaged?A. Have serviced by a Yamaha dealer.

Q. Is fuel joint connection incorrect?


Trouble Recovery

45

A. Connect correctly.

Q. Is heat range of spark plug incorrect?A. Inspect spark plug and replace it with rec-ommended type.

Q. Is high pressure fuel pump drive belt bro-ken?A. Have serviced by a Yamaha dealer.

Q. Is engine not responding properly to shiftlever position?A. Have serviced by a Yamaha dealer.

Engine vibrates excessively.Q. Is propeller damaged?A. Have propeller repaired or replaced.

Q. Is propeller shaft damaged?A. Have serviced by a Yamaha dealer.

Q. Are weeds or other foreign matter tangledon propeller?A. Remove and clean propeller.

Q. Is motor mounting bolt loose?A. Tighten bolt.

Q. Is steering pivot loose or damaged?A. Tighten or have serviced by a Yamahadealer.EMU29432

Temporary action in emergencyEMU29440

Impact damage

WARNINGEWM00870

The outboard motor can be seriously dam-aged by a collision while operating ortrailering. Damage could make the out-board motor unsafe to operate.

If the outboard motor hits an object in the wa-ter, follow the procedure below.

1. Stop the engine immediately.2. Inspect the control system and all compo-

nents for damage. Also inspect the boatfor damage.

3. Whether damage is found or not, returnto the nearest harbor slowly and careful-ly.

4. Have a Yamaha dealer inspect the out-board motor before operating it again.

EMU29532

Starter will not operateIf the starter mechanism does not operate(the engine cannot be cranked with the start-er), the engine can be started with an emer-gency starter rope.

WARNINGEWM01021

� Use this procedure only in an emergen-cy to return to the nearest port for re-pairs.

� When the emergency starter rope isused to start the engine, the start-in-gear protection device does not operate.Make sure the remote control lever is inneutral. Otherwise the boat could unex-pectedly start to move, which could re-sult in an accident.

� Attach the engine stop switch lanyard toa secure place on your clothing, or yourarm or leg while operating the boat.


Trouble Recovery

46

� Do not attach the lanyard to clothingthat could tear loose. Do not route thecord where it could become entangled,preventing it from functioning.


� Make sure no one is standing behindyou when pulling the starter rope. Itcould whip behind you and injure some-one.

� An unguarded, rotating flywheel is verydangerous. Keep loose clothing andother objects away when starting the en-gine. Use the emergency starter ropeonly as instructed. Do not touch the fly-wheel or other moving parts when theengine is running. Do not install thestarter mechanism or top cowling afterthe engine is running.

� Do not touch the ignition coil, spark plugwire, spark plug cap, or other electricalcomponents when starting or operatingthe motor. You could get an electricalshock.

EMU29561

Emergency starting engine1. Remove the top cowling.2. Remove the start-in-gear protection ca-

ble from the starter, if equipped.3. Remove the starter/flywheel cover after

removing the bolt(s).

4. Prepare the engine for starting. For fur-ther information, see page 20. Be surethe engine is in neutral and that the en-gine stop switch lanyard lock plate is at-tached to the engine stop switch. Themain switch must be “ ” (on), ifequipped.

5. If equipped the choke knob, pull out itwhen the engine is cold. After the enginestarts, gradually return the choke knob toits home position as the engine warmsup.

6. Insert the knotted end of the emergencystarter rope into the notch in the flywheelrotor and wind the rope several turnsaround the flywheel clockwise.

7. Give a strong pull straight out to crankand start the engine. Repeat if neces-sary.


Trouble Recovery

47

EMU29760

Treatment of submerged motorIf the outboard motor is submerged, immedi-ately take it to a Yamaha dealer. Otherwisesome corrosion may begin almost immediate-ly.If you cannot immediately take the outboardmotor to a Yamaha dealer, follow the proce-dure below in order to minimize engine dam-age.EMU29771

Procedure1. Thoroughly wash away mud, salt, sea-

weed, and so on, with fresh water.

2. Remove the spark plugs and face thespark plug holes downward to allow anywater, mud, or contaminants to drain.

3. Drain the fuel from the carburetor, fuel fil-ter, and fuel line.

4. Feed fogging oil or engine oil through thecarburetor(s) and spark plug holes whilecranking with the manual starter or emer-gency starter rope.

5. Take the outboard motor to a Yamahadealer as soon as possible.

CAUTION:ECM00400

Do not attempt to run the outboard motoruntil it has been completely inspected.

ZMU01909

ZMU01910

ZMU01911


YAMAHA MOTOR CO., LTD.

Printed on recycled paperPrinted in JapanApril 2006–0.8 × 1 CR


yamaha 4ac 5c manual

Documents

symptoms include

foreign matter

air vent screw

tilt support

checking painted

fuel system

warning system

rated horsepower