Fuel System Troubleshooting-Carburetor Related Causes Condition Possible Cause Conclusion 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. 22 KohlerEngines.com 66 690 01 Rev. C 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.