Service Manual

22
Fuel System
KohlerEngines.com 66 690 01 Rev. C
Troubleshooting-Carburetor Related Causes
Condition Possible Cause Conclusion
Engine starts hard, runs rough, or
stalls at idle speed.
Low idle fuel mixture (some models)/
speed improperly adjusted.
Adjust low idle speed tab, then adjust
low idle fuel needle.
Engine runs rich (indicated by black,
sooty exhaust smoke, misfi ring, loss
of speed and power, governor
hunting, or excessive throttle
opening).
Clogged air cleaner. Clean or replace air cleaner.
Choke partially closed during
operation.
Check choke lever/linkage to ensure
choke is operating properly.
Low idle fuel mixture is improperly
adjusted.
Adjust low idle fuel needle (some
models).
Float level is set too high. Adjust fl oat according to steps
outlined in repair kit installation
instructions.
Dirt under fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
Bowl vent or air bleeds plugged. Remove low idle fuel adjusting
needle. Clean vent, ports, and air
bleeds. Blow out all passages with
compressed air.
Leaky, cracked, or damaged fl oat. Submerge fl oat to check for leaks.
Engine runs lean (indicated by
misfi ring, loss of speed and power,
governor hunting, or excessive
throttle opening).
Low idle fuel mixture is improperly
adjusted.
Adjust low idle fuel needle (some
models).
Float level is set too low. Adjust fl oat according to steps
outlined in repair kit installation
instructions.
Idle holes plugged; dirt in fuel delivery
channels.
Remove low idle fuel adjusting
needle. Clean main fuel jet and all
passages; blow out with compressed
air.
Fuel leaks from carburetor. Float level set too high. Adjust fl oat according to steps
outlined in repair kit installation
instructions.
Dirt under fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
Bowl vents plugged. Blow out with compressed air.
Carburetor bowl gasket leaks. Replace gasket.
Fuel Shut-off Solenoid
Most carburetors are equipped with a fuel shut-off solenoid. Solenoid is attached to fuel bowl. Solenoid has a spring-
loaded pin that retracts when 12 volts is applied to lead, allowing fuel fl ow to main jet. When current is removed, pin
extends blocking fuel fl ow.
Below is a simple test, performed with engine off, that can determine if solenoid is functioning properly:
1. Shut off fuel and remove solenoid from carburetor. When solenoid is loosened and removed, gas will leak out of
carburetor. Have a container ready to catch fuel.
2. Wipe tip of solenoid with a shop towel or blow with compressed air to remove any remaining fuel. Take solenoid to
a location with good ventilation and no fuel vapors present. You will also need a 12 volt power source that can be
switched on and off.
3. Be sure power source is switched OFF. Connect positive power source lead to red lead of solenoid. Connect
negative power source lead to solenoid body.
4. Turn power source ON and observe pin in center of solenoid. Pin should retract with power ON and return to its
original position with power OFF. Test several times to verify operation.
Carburetor Circuits
Float
Fuel level in bowl is maintained by fl oat and fuel inlet needle. Buoyant force of fl oat stops fuel fl ow when engine is at
rest. When fuel is being consumed, fl oat will drop and fuel pressure will push inlet needle away from seat, allowing
more fuel to enter bowl. When demand ceases, buoyant force of fl oat will again overcome fuel pressure, rising to
predetermined setting and stop fl ow.