Kohler COMMAND CH18, Service Manual

Page: 39 / 232

5.6
Section 5
Fuel System and Governor
Troubleshooting Checklist
When the engine starts hard, runs roughly or stalls at
low idle speed, check the following areas before
adjusting or disassembling the carburetor.
• 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.
• Make sure fuel is reaching the carburetor. This
includes checking the fuel shut-off valve, fuel
tank filter screen, in-line fuel filter, fuel lines and
fuel pump for restrictions or faulty components
as necessary.
• Make sure the air cleaner base and carburetor are
securely fastened to the engine using gaskets in
good condition.
• Make sure the air cleaner element (including
precleaner if equipped) is clean and all air cleaner
components are fastened securely.
• Make sure the ignition system, governor system,
exhaust system, and throttle and choke controls
are operating properly.
If the engine is hard-starting, runs roughly, or stalls at
low idle speed, it may be necessary to adjust or service
the carburetor.
High Altitude Operation
When operating the engine at altitudes of 1500 m
(5000 ft.) and above, the fuel mixture tends to get over-
rich. This can cause conditions such as black, sooty
exhaust smoke, misfiring, loss of speed and power,
poor fuel economy, and poor or slow governor
response.
To compensate for the effects of high altitude, special
high altitude jet kits are available. The kits include a
new main jet, slow jet (where applicable), necessary
gaskets and O-Rings. Refer to the parts manual for the
correct kit number.
Fuel Shut-off Solenoid
Most carburetors are equipped with a fuel shut-off
solenoid. The solenoid is attached in place of the fixed
main jet screw on the flywheel side of the carburetor.
See Figure 5-4. The solenoid has a spring-loaded pin
that retracts when 12 volts is applied to the lead,
allowing fuel flow through the main jet.
When current is removed the pin extends blocking
the main fuel jet and preventing fuel from entering
the carburetor.
Figure 5-4. Fuel Shut-off Solenoid.
Below is a simple test, made with the engine off, that
can determine if the solenoid is functioning properly:
1. Shut off fuel and remove the solenoid from the
carburetor. When the solenoid is loosened and
removed, gas will leak out of the carburetor.
Have a container ready to catch the fuel.
2. Wipe the tip of the solenoid with a shop towel or
blow it off with compressed air, to remove any
remaining fuel. Take the solenoid to a location
with good ventilation and no fuel vapors present.
You will also need a 12 volt power source that can
be switched on and off.
3. Be sure the power source is switched “off”.
Connect the positive power source lead to the red
lead of the solenoid. Connect the negative power
source lead to the solenoid bracket.
4. Turn the power source “on” and observe the pin
in the center of the solenoid. The pin should
retract with the power “on” and return to its
original position with the power off. Test several
times to verify operation.
Fuel Shut-off Solenoid
Two-Barrel Carburetor
Fuel Shut-off Solenoid
One-Barrel Carburetor