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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: 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.
• Make sure the proper fuel filter is being used, and
it is clean and unobstructed. Replace filter only
with genuine Kohler parts.
• Make sure all connections to sensors, ECU, and
fuel injectors are properly secured.
• Make sure a good 12 volt battery is being used
and is fully charged.
If these checks do not correct the problem, or the MIL
remains on, further diagnosis and servicing by an
authorized Kohler Engine Dealer is necessary.
Adjustment – EFI Throttle Body
Low Idle Speed (RPM) is the only adjustment that
can be made. All other fuel calibrations are controlled
by the ECU. The standard low idle speed is 1500 RPM*
(± 75 RPM).
*NOTE: The actual low idle speed depends on the
application -- refer to equipment
manufacturer's recommendations.
When an EFI engine is started cold, the ECU will
briefly set a higher (200-400 RPM) low idle speed,
similar to a fast idle. Do not attempt to perform any
readjustment during this "warm-up" period.
If adjustment is to be made, the engine must be at
operating temperature, air cleaner in place, and check
engine light must be off (no fault codes present).
1. Start the engine and run at half throttle for 5 to
10 minutes to warm up.
2. Place the throttle control into the idle or slow
position.
3. Turn the low idle speed adjusting screw in or out
and check RPM with a tachometer. See Figure 24.
Figure 24. EFI Throttle Body Manifold.
Troubleshooting
When troubles occur, be sure to check the simple
causes which, at first, may seem too obvious to be
considered. For example, a starting problem could be
caused by an empty fuel tank. Some common causes of
engine troubles are listed in the following table.
Do not attempt to service or replace major engine
components, or any items that require special timing
or adjustment procedures. Have your Kohler Engine
Service Dealer do this work.
Fuel Rail
Throttle Body
Intake Manifold
Low Idle Speed
Adjusting Screw