15
Figure 18. Carburetor CV17-25, CV675-740.
Troubleshooting
If engine troubles are experienced that appear to be
fuel system related, check the following areas before
adjusting the carburetor.
Fuel Line
EFI Engines: A special fuel line, capable of
withstanding the high pressure of the EFI fuel system,
is used (must meet SAE R9 specifications). See Figure
17. If fuel line must be replaced, see your Kohler
Engine Service Dealer.
Carburetor Troubleshooting and
Adjustments
NOTE: Carburetor adjustments should be made
only after the engine has warmed up.
The carburetor is designed to deliver the correct
fuel-to-air mixture to the engine under all operating
conditions. The high idle mixture is set at the factory
and cannot be adjusted. The low idle fuel adjusting
needle (if equipped) is also set at the factory and
normally does not need adjustment.
NOTE: To ensure correct engine operation at
altitudes above 1525 meters (5000 ft.), 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.
• 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.
• 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: Certified engines may have a fixed idle fuel
adjusting needle. Do not attempt steps 1 and
2 below. Proceed directly to step 3.
1. With the engine stopped, turn the low idle fuel
adjusting needle in (clockwise) until it bottoms
lightly.
NOTE: The tip of the low idle fuel adjusting
needle is tapered to critical dimensions.
Damage to the needle and the seat in
carburetor body will result if the needle is
forced.
2. Preliminary Settings: Turn the adjusting needle
out (counterclockwise) from lightly bottomed
2-1/4 turns.
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 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.
Idle Speed
Adj. Screw
& Spring
Idle Fuel
Adj. Needle
& Spring
Fuel Shut-Off
Solenoid
(some engines
equipped with)
