Engines in this series are equipped with a two-barrel side-draft carburetor with fixed main jets on a matching intake
manifold. Carburetor features a self-relieving choke, serviceable slow jets, main jets, accelerator pump, and a fuel
shutdown solenoid.
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 filled 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 filter screen,
in-line fuel filter, 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 speed improperly adjusted. Adjust idle speed/governed idle tab.
Engine runs rich (indicated by black,
sooty exhaust smoke, misfiring, 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.
Float level is set too high.
Adjust float according 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. Clean vent, ports, and air
bleeds. Blow out all passages with
compressed air.
Engine runs lean (indicated by
misfiring, loss of speed and power,
governor hunting, or excessive
throttle opening).
Float level is set too low.
Adjust float according to Float
Replacement Procedure.
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 is set too high.
Adjust float according 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
23
24 690 37 Rev. B
KohlerEngines.com
