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
i
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?
1
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
4
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
5
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.
6
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.
1
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
____________________
____________
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
2
Install new throttle shaft
Reuse fiber washer from old throttle
shaft; insert throttle shaft into carburetor;
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
3
Replace carburetor on fuel tank
Use roll pin and Teflon washer from repair
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
4