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CH26 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.
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 permanently
preset and 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 14.
Figure 14.
Low Idle Speed
Adjusting Screw
Fuel Rail
Throttle Body
Intake Manifold