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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.
• 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 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.
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 •••
Figure 17. EFI Throttle Body Manifold.
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 17.