Carburetor Troubleshooting and
Adjustments
in compliance with government emission standards,
the carburetor is calibrated to deliver the correct fuel-
to-air mixture to the engine under all operating
conditions. The high speed mixture is set at the
factory and cannot be adjusted. The low idle fuel
adjustment screw (if equipped) is also set at the
factory and normally does not require adjustment. See
Figure 15.
Figure 15. Carburetor.
Make sure fuel is reaching the carburetor. This
includes checking the fuel lines and fuel pump for
restrictions or faulty components, replace as
necessary.
* Make sure the air cleaner element is clean and all
air cleaner element components are fastened
securely.
if, after checking the items listed above, the engine is
hard to start, runs roughly, or stalls at low idle speed,
it may be necessary to adjust or service the
carburetor.
Adjust Carburetor
NOTE: Some engines may have a fixed (capped) idle
fuel adjusting screw or limiter cap. On these
engines, do not attempt steps 1 and 2 below.
Proceed directly to Step 3. On limiter
equipped models, adjustment can only be
performed within the limits allowed by the
cap.
.
Idle Fuel Adjustment: with the engine stopped,
turn the low idle fuel adjusting screw in
(clockwise) until it bottoms lightly. See Figures 15
and 16.
NOTE:
The tip of the low idle fuel adjusting screw is
tapered to critical dimensions. Damage to the
needle tip and the seat in carburetor body
will result if the needle is forced.
2. Preliminary Settings: Turn the adjusting screw
out (counterclockwise) from lightly bottomed
2-1/4 turns.
Figure 16. Carburetor Adjustment Access Locations
(Latch Removed For Clarity).
Troubleshooting
if engine troubles are experienced that appear to be
fuel system related, check the following areas before
adjusting the carburetor.
12
Make sure the fuel tank is filled with clean, fresh
gasoline.
Make sure the fuel tank cap vent is not blocked
and that it is operating properly.
if the fuel tank is equipped with a shut-off valve,
make sure it is open.
if the engine is equipped with an in-line fuel filter,
make sure it is clean and unobstructed. Replace
the filter if necessary.
3. Start the engine and run at half throttle for 5 to 10
minutes to warm up. The engine must be warm
before making final settings (steps 4, 5, and 6).
4.
Low Idle Speed (RPM) Setting: Place the throttle
control into the "idle" or "slow" position. Set the
low idle speed to 1200 RPM* (+ 75 RPM) by
turning the low idle speed adjusting screw in or
out. Check the speed using a tachometer.
*NOTE:
The actual low idle speed depends on the
application - refer to equipment
manufacturer's recommendations. The
recommended low idle speed for basic
engines is 1200 RPM. To ensure best results
when setting the low idle fuel needle, the low
idle speed must not exceed 1200 RPM
(+ 75 RPM).
5. if proper operation is not restored after adjusting,
carburetor servicing by an authorized Kohler
Engine Service Dealer may be required.
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