Small Gas Engine: Carburetor - I Supplement for CEV #886

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Small Gas Engine: Carburetor – I

Supplement for CEV #886

Goal: To introduce the different steps of disassembly and assembly of carburetors used on small gas engines. Objectives:

1. to learn how to disassemble and assemble a Vacu-Jet carburetor 2. to understand the disassembly and assembly of a Flo-Jet

carburetor

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Small Gas Engine: Carburetor – I

Quiz I

True or False ____1. The Vacu-Jet carburetor has one plastic fuel pickup tube. ____2. Vertically shafted engines often have a Vacu-Jet carburetor. ____3. Carburetor cleaner is very caustic and carburetors should not remain in the solvent for more than 25 to 30 minutes. Short Answer 4. What device controls the amount of fuel taken into the carburetor? 5. What three things are included in the needle valve repair kit? 6. After seating the needle valve, how many turns should it be backed out for initial adjustment?

7. How full should the fuel tank be when making adjustments to the high speed needle valve?

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Small Gas Engine: Carburetor - I Quiz II

True or False ____1. To avoid damage, the high speed needle valve should be removed before disassembling the carburetor. ____2. The venturi is a narrow passageway which increases air velocity, thereby creating a low pressure area which draws in fuel. ____3. All Flo-Jet carburetors are built the same. Short Answer 4. What is the function of the float? 5. How is the float adjusted? 6. What can be used to clean the carburetor nozzle?

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Small Gas Engine: Carburetor - I Final Quiz

True or False ____1. Carburetors should be left in carburetor cleaner overnight to ensure thorough cleaning. ____2. The venturi maintains a constant fuel level in the Flo-Jet carburetor. ____3. On a Flo-Jet carburetor, the housing screws should not be tightened until the nozzle has been installed. ____4. On a Vacu-Jet carburetor, the fuel tank should be full when adjusting the

high speed needle valve. Multiple Choice ____5. After seating the needle valve, how many turns should it be backed out for initial adjustment? a. 1/2 turn b. 1 turn c. 1-1/2 turns d. 2 turns ____6. What controls the amount of fuel taken into the carburetor? a. throttle b. choke c. float d. high speed needle valve Short Answer 7. How many fuel pickup tubes does a Vacu-Jet carburetor have?

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8. Are Vacu-Jet carburetors normally found on vertically shafted engines or horizontally shafted engines?

9. What is the preferred tool to use when removing the needle valve seat? 10. During high speed operations, how does fuel enter a Flo-Jet carburetor?

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Small Gas Engine: Carburetor – I Answer Key for CEV #886

Quiz I True or False T 1. The Vacu-Jet carburetor has one plastic fuel pickup tube. F 2. Vertically shafted engines often have a Vacu-Jet carburetor. Horizontally shafted engines often have a Vacu-Jet type carburetor. T 3. Carburetor cleaner is very caustic and carburetors should not remain in the solvent for more than 25 to 30 minutes. Short Answer 4. What device controls the amount of fuel taken into the carburetor? High speed needle valve 5. What three things are included in the needle valve repair kit? Needle valve, seat, and washer 6. After seating the needle valve, how many turns should it be backed out for initial adjustment? 1-1/2 turns

7. How full should the fuel tank be when making adjustments to the high speed needle valve?

1/2 full

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Small Gas Engine: Carburetor - I Answer Key for CEV #886

Quiz II

True or False T 1. To avoid damage, the high speed needle valve should be removed before disassembling the carburetor. T 2. The venturi is a narrow passageway which increases air velocity, thereby creating a low pressure area which draws in fuel. F 3. All Flo-Jet carburetors are built the same. Many Flo-jets display manufacturers’ differences. Short Answer 4. What is the function of the float? It maintains a constant fuel level in the carburetor. 5. How is the float adjusted? By bending the tang, which controls the fuel level needle valve. 6. What can be used to clean the carburetor nozzle? A welding tip cleaner.

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Small Gas Engine: Carburetor - I Answer Key for CEV #886

Final Quiz

True or False F 1. Carburetors should be left in carburetor cleaner overnight to ensure thorough cleaning. F 2. The venturi maintains a constant fuel level in the Flo-Jet carburetor. T 3. On a Flo-Jet carburetor, the housing screws should not be tightened until the nozzle has been installed. F 4. On a Vacu-Jet carburetor, the fuel tank should be full when adjusting the high speed needle valve. Multiple Choice c 5. After seating the needle valve, how many turns should it be backed out for initial adjustment? a. 1/2 turn b. 1 turn c. 1-1/2 turns d. 2 turns d 6. What controls the amount of fuel taken into the carburetor? a. throttle b. choke c. float d. high speed needle valve Short Answer 7. How many fuel pickup tubes does a Vacu-Jet carburetor have? One 8. Are Vacu-Jet carburetors normally found on vertically shafted engines or horizontally shafted engines? Horizontally shafted engines

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9. What is the preferred tool to use when removing the needle valve seat? Carburetor nozzle tool 10. During high speed operations, how does fuel enter a Flo-Jet carburetor? Through holes in the nozzle.

Small Gas Engine: Carburetor - II Supplement for CEV #887

Small Gas Engine: Carburetor - II

Supplement for CEV #887

Goal: The student follows the procedures necessary for the maintenance, disassembly, and assembly of Pulsa-Jet Carburetors. Objectives: 1. to learn the appropriate techniques used to disassemble and assemble a

Pulsa-Jet Carburetor for horizontally shafted engines 2. to understand the correct steps needed to disassemble and assemble a

Pulsa-Jet carburetor for vertically shafted engines

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Small Gas Engine: Carburetor – II

Quiz I

True or False ____1. The Pulsa-Jet has two fuel pickup tubes. ____2. The diaphragm serves as a fuel pump. ____3. The throttle butterfly is difficult to replace, due to its location within the carburetor itself. ____4. A screwdriver is used to remove the seat underneath the needle valve. Short Answer 5. If the long pickup tube enters the main fuel tank, where does the short pickup tube enter? 6. When replacing the diaphragm, where should the spring and cup washer be placed?

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Small Gas Engine: Carburetor - II ]Quiz II

True or False ____1. The Pulsa-Jet carburetor for vertically shafted engines has an automatic choke. ____2. It is acceptable to replace the needle valve without replacing the seat. ____3. The automatic choke should be tripped before attaching the choke linkage cover. Multiple Choice ____4. What is used to repair a warped fuel tank?

a. repair kit with Teflon washer and roll pin b. warped tanks must be replaced c. fuel tanks do not warp

Short Answer 5. Why should the O-rings be replaced? 6. How can one detect a warped fuel tank? 7. When replacing the diaphragm, should the spring and cup washer be placed in the top of the fuel tank? 8. What is the washer from the fuel tank repair kit made of?

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Small Gas Engine: Carburetor - II Final Quiz

True or False ____1. The cup washer protects the diaphragm from the sharp end of the spring. ____2. When replacing the diaphragm on a Pulsa-Jet for vertically shafted engines, the spring should be placed inside the carburetor. ____3. If the needle valve is replaced, the seat should be replaced as well. ____4. A Pulsa-Jet carburetor for vertically shafted engines must be turned upside down for removal from the fuel tank. Multiple Choice ____5. What is used to check a fuel tank for warping?

a. straight edge b. tape measure c. .002” thickness gauge d. both a and c are used

____6. What parts are included in the needle valve repair kit?

a. washer b. needle valve c. seat d. all of the above

Short Answer 7. What should be done to the needle valve before installing it? 8. What does the throttle butterfly attach to? 9. On a Pulsa-Jet for vertically shafted engines, what should be done before tightening the carburetor mounting screws? 10. What is the purpose of the well within the fuel tank?

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Small Gas Engine: Carburetor – II Answer Key for CEV #887

Quiz I True or False T 1. The Pulsa-Jet has two fuel pickup tubes. T 2. The diaphragm serves as a fuel pump. T 3. The throttle butterfly is difficult to replace, due to its location within the carburetor itself. F 4. A screwdriver is used to remove the seat underneath the needle valve.

Remove the seat with a carburetor nozzle tool. A screwdriver can score the threads or damage the seat.

Short Answer 5. If the long pickup tube enters the main fuel tank, where does the short pickup tube enter? A fuel well within the tank where fuel stays at a constant level. 6. When replacing the diaphragm, where should the spring and cup washer be placed? The spring and cup washer should be underneath the diaphragm

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Small Gas Engine: Carburetor - II Answer Key for CEV #887

Quiz II True or False T 1. The Pulsa-Jet carburetor for vertically shafted engines has an automatic choke. F 2. It is acceptable to replace the needle valve without replacing the seat. Always replace all parts—seat, washer, and needle valve—at the same time. T 3. The automatic choke should be tripped before attaching the choke linkage cover. Multiple Choice a 4. What is used to repair a warped fuel tank?

a. repair kit with Teflon washer and roll pin b. warped tanks must be replaced c. fuel tanks do not warp

Short Answer 5. Why should the O-rings be replaced? They are inexpensive and vital to maintaining a good seal. 6. How can one detect a warped fuel tank? measuring with a straight edge and thickness gauge 7. When replacing the diaphragm, should the spring and cup washer be placed in the top of the fuel tank ?

No, they should be installed in the carburetor and the diaphragm placed on top of the cup washer.

8. What is the washer from the fuel tank repair kit made of? Teflon

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Small Gas Engine: Carburetor - II Answer Key for CEV #887

Final Quiz

True or False T 1. The cup washer protects the diaphragm from the sharp end of the spring. F 2. When replacing the diaphragm on a Pulsa-Jet for vertically shafted engines, the spring should be placed inside the carburetor. T 3. If the needle valve is replaced, the seat should be replaced as well. T 4. A Pulsa-Jet carburetor for vertically shafted engines must be turned upside down for removal from the fuel tank. Multiple Choice d 5. What is used to check a fuel tank for warping ?

a. straight edge b. tape measure c. .002” thickness gauge d. both a and c are used

d 6. What parts are included in the needle valve repair kit ?

a. washer b. needle valve c. seat d. all of the above

Short Answer 7. What should be done to the needle valve before installing it ? turned out to prevent damage 8. What does the throttle butterfly attach to ? the throttle shaft 9. On a Pulsa-Jet for vertically shafted engines, what should be done before tightening the carburetor mounting screws. Load the choke. 10. What is the purpose of the well within the fuel tank ? It maintains a constant level fuel supply for the carburetor.

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Small Gas Engine: Carburetor - II

Supplement for CEV #887 Small Gas Engine: Carburetor - II is the second in a two-part series featuring the identification of parts, disassembly, repair and reassembly of the Briggs and Stratton horizontal Pulsa-Jet and vertical Pulsa-Jet carburetors. Dr. David Lawver, Associate Professor of Agricultural Education and Communications at Texas Tech University, demonstrates the proper procedures for removing and replacing the diaphragm, needle valve assembly and throttle shaft. Checking the fuel tank for warping is also demonstrated. Enhanced Learning! This production incorporates CEV’s VideoActive format, which has been designed to create an interactive learning environment by incorporating questions and discussion into each program. Color and numeric coding for each section make selection of a desired topic or review of specific information much easier and faster. Following each section, a short quiz will be presented. A comprehensive ten question final quiz will be presented at the end of each part. Included in this teaching guide are corresponding copy-ready student quizzes, a teacher’s key, an outline for performing the procedures demonstrated in this production and additional information sheets regarding each Pulsa-Jet carburetor. Easy-to-use Format: This teaching guide is designed to follow the material as it is presented in the presentation. The enclosed outline briefly describes the procedures performed. Next to each procedure, remarks concerning the tools that are used to complete the procedure and any special instructions are listed. This format enables the viewer to follow along with the production and it serves as a guide when performing the procedures after viewing.

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Small Gas Engine: Carburetor - II

Tools and equipment needed: flat blade screwdriver, 1/2” combination wrench, carburetor nozzle tool, mixture adjustment screwdriver, long nose pliers, holding screwdriver, straight edge (small square), thickness gauge

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Procedure Remarks PULSA-JET CARBURETOR FOR

HORIZONTALLY SHAFTED ENGINES Remove diaphragm cover Use flat blade screwdriver Replace diaphragm Cup washer should cover the spring and be placed below the diaphragm; align and install new diaphragm Replace diaphragm cover Use flat blade screwdriver; tighten using an alternating sequence Remove needle valve Use 1/2” combination wrench Remove needle valve seat Use carburetor nozzle tool Install new needle valve repair kit Use carburetor nozzle tool; turn needle valve out before installing; use 1/2” combination wrench Adjust needle valve After seating needle valve, turn it out 1 1/2 turns using a mixture adjustment screwdriver; do not over tighten when seating Inspect throttle shaft Move side to side and check for slack Remove throttle shaft Remove spiral in throat of carburetor; use small flat blade screwdriver and remove throttle butterfly; lift throttle shaft out Install new throttle shaft Reuse fiber washer from old throttle shaft; insert throttle shaft into carburetor;

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use a holding screwdriver to start screw when installing throttle butterfly; insert spiral into carburetor throat Tools and equipment needed: flat blade screwdriver, 1/2” combination wrench, carburetor nozzle tool, mixture adjustment screwdriver, long nose pliers, holding screwdriver, straight edge (small square), thickness gauge

Procedure Remarks PULSA-JET CARBURETOR FOR

VERTICALLY SHAFTED ENGINES Remove choke linkage cover Use flat blade screwdriver Disconnect choke linkage Pull linkage out of choke arm assembly Remove carburetor from fuel tank Remove screws using flat blade screwdriver; note special screws used to attach carburetor to fuel tank; with fuel tank empty, turn carburetor and tank upside down and carefully lift tank off of carburetor Check fuel tank for warping Fuel tank must be level; use a straight edge and .002” thickness gauge Remove diaphragm Replace if torn or excessively worn Remove needle valve Use 1/2” combination wrench Remove seat Use carburetor nozzle tool Install new needle valve repair kit Use carburetor nozzle tool; turn needle valve out before installing; use 1/2” combination wrench Adjust needle valve After seating needle valve, turn it out 1 1/2 turns using a mixture adjustment screwdriver; do not over tighten when seating Install diaphragm Install spring and cup washer into carburetor; install spring in kit on new diaphragm Replace carburetor on fuel tank Use roll pin and Teflon washer from repair

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kit if fuel tank is warped; turn carburetor upside down and align fuel pickup tubes, diaphragm spring and roll pin; replace all screws but do not tighten Load the choke Move the choke butterfly to an over center position and reattach linkage to choke arm assembly; tighten carburetor screws in a staggered sequence Replace choke linkage cover Trip the choke so the choke butterfly is fully closed; replace cover and gasket; use flat blade screwdriver Replace O-ring Install new O-ring in groove in throttle bore Inspect throttle shaft Move side to side and check for slack; replace if necessary

Small Gas Engines: Carburetor Supplement for DVD CEV80886

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Web Sites for Small Gas Engines: Carburetor

Agricultural Mechanics Transparencies http://cast.csufresno.edu/agedweb/agmech/graphics/toc.htm Carburetor Troubleshooting http://www.recarbco.com/technical/newtrouble.html Carburetor Information Power Point http://www.foukeffa.org/ Disassembly of Lawn Mower Engine http://www.lawn-mower-shop.com/titlesli.htm Small Engines http://www.small-engines.com Briggs and Stratton Engines http://www.briggsandstratton.com Tecumseh Engines http://www.tecumseh.com Kohler Engines http://www.kohlerengines.com Kawasaki http://www.kawasaki.com/ Small Tractor FAQ http://www.andrew.cmu.edu/user/kb13/maint_sb.htm Do It Yourself Guide http://www.jackssmallengines.com/do_it_home.html