Electronic Control System Gas Plus Engines – 019-049   Fuel Shutoff Valve Circuit

The fuel shutoff solenoid valve is mounted in the entrance to the fuel mixer housing on the engine. The solenoid is controlled by the ECM.

NOTE: Only one wire from the ECM will be attached to the solenoid post. The ECM is not capable of supplying power for other auxiliary components. If an external voltage source is attached, a fault code will be induced.

The solenoid will open when the ECM senses the vehicle keyswitch is turned on and engine speed is detected. The solenoid will close when the ECM senses the vehicle keyswitch is turned off or when the ECM senses an engine overspeed, or if the engine speed stops.

Check for continuity between voltage supply pins on the harness side of the fuel shutoff valve connector and the ECM connector. Check also for continuity between return pins on the harness side of the engine position sensor connector and the ECM connector.

Disconnect the engine position sensor and the fuel shutoff connector from the engine harness. Disconnect engine harness ECM connector 1 from the ECM.

Measure the resistance from the voltage supply pin in the fuel shutoff harness connector to the corresponding fuel shutoff voltage supply pin in ECM connector 1.

Repeat the resistance check from the return pins in the engine position sensor connector to the corresponding engine position sensor return pins in ECM connector 1.

If there is no continuity, repair or replace the engine harness. Refer to Procedure 019-205 or 019-204 to repair the harness, and Procedure 019-043 to replace the harness.

Check for continuity between signal pins on the harness side of the engine position sensor connector and ground. Measure the resistance from the signal pins in the engine position sensor harness connector to engine block ground.

If there is no continuity, repair or replace the engine harness. Refer to Procedure 019-205 to repair the harness, and Procedure 019-043 to replace the harness.

Disconnect the engine position sensor from the engine harness. Disconnect engine harness ECM connector 1 from the ECM. Set the multimeter to measure resistance. Measure the resistance from the return pin in the engine position sensor harness connector to engine block ground.

The multimeter must show a measurement of 100k ohms or more. If the measurement is less than 100k ohms, repair or replace the engine harness. Refer to Procedure 019-205 to repair the harness, and Procedure 019-043 to replace the harness.

Disconnect the engine position sensor from the engine harness. Disconnect both engine harness ECM connectors from the ECM. Measure the resistance from the voltage supply pins in ECM connector 1 to all other pins in the connector.

Measure the resistance from the voltage supply pins in ECM connector 1 to all pins in ECM connector 2.

The multimeter must show a measurement of 100k ohms or more. If the measurement is less than 100k ohms, repair or replace the engine harness. Refer to Procedure 019-205 to repair the harness, and Procedure 019-043 to replace the harness.