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Figure 16. Carburetor (CH18-25,CH730,740).
Troubleshooting
If engine troubles are experienced that appear to be
fuel system related, check the following areas before
adjusting 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.
• 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
There are no accessible mixture adjustment screws on
the carburetor. The only setting which can be changed
is the low idle speed.
1. 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 2 and 3).
2. 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.
*NOTE: The actual low idle speed depends on the
application – refer to equipment
manufacturers recommendations. The
standard low idle speed is 1200 RPM.
3. If proper operation is not restored after adjusting
the low idle speed, carburetor servicing by an
authorized Kohler Engine Service Dealer may be
required.
Electronic Fuel Injection (EFI) System
The EFI system is a complete, electronically-controlled
fuel management system, designed to deliver a
precisely controlled fuel flow under all operating
conditions. The electronic control unit (ECU), the
‘‘brain’’ of the system, automatically adjusts fuel
delivery and ignition timing based upon load, speed,
operating temperature, and exhaust emission levels.
The low idle speed is the only manual adjustment
possible.
The ECU continuously monitors operation of the EFI
system. If it detects a problem or fault within the
system, it will illuminate the malfunction indicator light
(MIL), which is mounted in view of the operator. This is
a signal that normal, programmed operation has been
affected, and service by an authorized Kohler Engine
Dealer is required.
NOTE: The EFI system requires a rather complex
wiring harness to carry the electrical signals
between the sensors and the ECU. Do not
spray water at the wiring harness or any of the
electrical components, especially the ECU, as
it could cause malfunction, damage, or failure.
Troubleshooting
If the MIL comes on, or the engine becomes hard to
start, runs roughly, or stalls at low idle speed, initial
checks should be made in the following areas:
• Make sure the fuel tank is filled with clean, fresh
gasoline, and shut-off valve (if so equipped) is
opened completely.
• Make sure fuel tank vent cap is not blocked and it
is operating properly.
• Make sure the air cleaner element and precleaner
are clean and all components are properly
secured. Clean or replace as necessary.
Low Idle
Speed Adj.
Screw
Low Idle
Fuel Adj.
Needle &
Spring
Fixed Main Jet
(under optional
solenoid)