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Fuel System
22 690 01 Rev. -- KohlerEngines.com
Troubleshooting-Carburetor Related Causes
Condition Possible Cause Conclusion
Engine starts hard, runs rough, or
stalls at idle speed.
Low idle fuel mixture/speed
improperly adjusted.
Adjust low idle speed screw, then
adjust low idle fuel needle.
Improper choke adjustment. Correct choke adjustment.
Engine runs rich (indicated by black,
sooty exhaust smoke, misfi ring, loss
of speed and power, governor
hunting, or excessive throttle
opening).
Choke partially closed during
operation.
Check choke lever/linkage to ensure
choke is operating properly.
Dirt under fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
Bowl vent or air bleeds plugged. Remove fuel bowl. Clean vent, ports,
and air bleeds. Blow out all passages
with compressed air.
Fuel bowl O-ring leaks. Remove fuel bowl and replace
O-ring.
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).
Idle holes plugged; dirt in fuel
delivery channels.
Remove fuel bowl. Clean main fuel
jet and all passages; blow out with
compressed air.
Fuel leaks from carburetor. Dirt under fuel inlet needle. Remove fuel bowl. Clean vent, ports,
and air bleeds. Blow out all passages
with compressed air.
Float is cracked or damaged. Replace fl oat.
Carburetor solenoid gasket
damaged.
Replace gasket.
Bowl retaining screws loose. Torque screws to 4.0 N·m (35 in. lb.).
FUEL SYSTEM
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 either terminal of solenoid and
negative lead to other terminal of solenoid.
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.
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