Kohler Command CH620 - Manual (Page 17)

17
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.
Figure 22. 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.
When an EFI engine is started cold, the ECU will be
using internal programming for cold running, and the
idle speed may vary from the manual setting. 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 22.
Low Idle Speed
Adjusting Screw
Fuel Rail
Throttle Body
Intake Manifold
Will Not Start • • • • • • •
Hard Starting • • • • • •
Possible Cause No Improper Dirt In Dirty Incorrect Engine Dirty Air Faulty
Problem Fuel Fuel Fuel Line/System Grass Screen Oil Level Overloaded Cleaner Spark Plug
Stops Suddenly • • • • • •
Lacks Power • • • • • • •
Operates Erratically • • • • • •
Knocks or Pings • • • •
Skips or Misfires • • • • •
Backfires • • • •
Overheats • • • • •
High Fuel Consumption • • •
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.