5.5
Section 5
Fuel System and Governor
5
Troubleshooting - Carburetor Related Causes
Condition Possible Cause/Probable Remedy
1. Engine starts hard, runs roughly or stalls at idle
speed.
1. Low idle fuel mixture (some models)/speed
improperly adjusted. Adjust the idle speed screw
or the idle mixture screw.
2. Engine runs rich (indicated by black, sooty
exhaust smoke, misfi ring, loss of speed and
power, governor hunting, or excessive thro le
opening).
2a. Clogged air cleaner. Clean or replace.
b. Choke partially closed during operation. Check
the choke lever/linkage to ensure choke is
operating properly.
c. Low idle fuel mixture is improperly adjusted.
Adjust idle mixture screw.
d. Dirt under the fuel inlet needle. Remove needle;
clean needle and seat and blow with compressed
air.
e. 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.
f. Leaky, cracked or damaged fl oat. Submerge fl oat
to check for leaks.
3. Engine runs lean (indicated by misfi ring, loss of
speed and power, governor hunting or excessive
thro le opening).
3a. Intake air leak. Check if carburetor is loose or one
of the intake gaskets is leaking.
b. Idle holes plugged; dirt in fuel delivery channels.
Clean main fuel jet and all passages; blow out
with compressed air.
4. Fuel leaks from carburetor. 4a. Float damaged. See Remedy 2f. Replace fl oat.
b. Dirt under fuel inlet needle. See Remedy 2d.
c. Bowl vents plugged. Blow out with compressed
air.
d. Carburetor bowl gasket leaks. Replace gasket.
Carburetor
These engines are equipped with a fi xed main jet
carburetor. The carburetor is designed to deliver the
correct fuel-to-air mixture to the engine under all
operating conditions. The idle mixture is set at the
factory and cannot be adjusted. The low idle fuel
adjusting needle is also set at the factory and has a
limiting cap. It normally does not need adjustment.
Adjustments
General
NOTE: Carburetor adjustments should be made only
a er the engine has warmed up.
NOTE: Certifi ed engines have a limiter cap on the
idle fuel adjusting needle. Adjustments can
only be performed within the limits allowed
by the cap.
High-Altitude Operation
Operating the engine with the wrong engine
confi guration at a given altitude may increase
its emissions and decrease fuel effi ciency and
performance. To ensure correct engine operation
at altitudes above 1219 meters (4000 ), it may be
necessary to have an authorized Kohler dealer install
a special high altitude jet kit in the carburetor. If a
high altitude kit has been installed, the engine must
be reconverted to the original jet size, before it is
operated at lower altitudes, or overheating and engine
damage can result.
To obtain high altitude kit information or locate a
dealer near you, call 1-800-544-2444 to fi nd the names
of the nearest Kohler Co. Service Centers or, access
our web site at: www.kohlerengines.com and click on
the “Service & Dealer Locator” located in the upper
right hand corner. The service center will need your
engine specifi cation number which is found on your
Engine ID Label.
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