Adjustment – efi throttle body, Troubleshooting – Kohler Command CH620 User Manual

Page 17

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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.

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