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.

Low Idle Speed

Adjusting Screw

Throttle Body

Intake Manifold

Fuel Rail

Figure 14.

14