Troubleshooting Checklist
When engine starts hard, runs roughly or stalls at low idle speed, check following areas before adjusting or
disassembling carburetor.
1. Make sure fuel tank is fi lled with clean, fresh gasoline.
2. Make sure fuel tank cap vent is not blocked and that it is operating properly.
3. Make sure fuel is reaching carburetor. This includes checking fuel shut-off valve, fuel tank fi lter screen, in-line fuel
fi lter, fuel lines and fuel pump for restrictions or faulty components as necessary.
4. Make sure air cleaner base and carburetor are securely fastened to engine using gaskets in good condition.
5. Make sure air cleaner element (including precleaner if equipped) is clean and all air cleaner components are
fastened securely.
6. Make sure ignition system, governor system, exhaust system, and throttle and choke controls are operating
properly.
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 (some models).
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 (some models)
is improperly adjusted.
Adjust low idle fuel needle (some
models).
Float level is set too high. Refer to Float Replacement
Procedure.
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
(some models). 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 (some models)
is improperly adjusted.
Adjust low idle fuel needle (some
models).
Float level is set too low. Refer to Float Replacement
Procedure.
Idle holes plugged; dirt in fuel delivery
channels.
Remove low idle fuel adjusting needle
(some models). Clean main fuel jet
and all passages; blow out with
compressed air.
Fuel leaks from carburetor. Float level is set too high. Refer to Float Replacement
Procedure.
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 System
2724 690 06 Rev. P KohlerEngines.com
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