GM Service Manual Online
For 1990-2009 cars only

Checks

Action

DEFINITION: The engine cranks OK, but does not start for a long time. The engine does eventually run, or may start but immediately dies.

Preliminary Checks

    • Refer to Important Preliminary Checks in Symptoms .
    • Make sure the vehicle operator is using the correct starting procedure.

Sensor Checks

    • Check the ECT sensor for proper operation by performing the following:
        1. Allow the engine temperature to reach ambient air temperature by leaving the engine OFF for several hours (overnight for most accurate results).
        2. Turn the ignition ON while leaving the engine OFF.
        3. Using a scan tool compare the ECT and IAT sensors displayed temperature.

The sensors should be within 3°C (5°F) of each other.

        4. Replace the ECT sensor or repair the ECT sensor circuit if the ECT is not near the expected value.
    • Check the TP sensor for proper operation.
        With the throttle blade fully at rest the monitored TP sensor voltage on a scan tool should be LESS than 0.85 volts.
        If the TP sensor is not near the expected voltage check for the following conditions:
       - A faulty TP sensor.
       - A faulty TP sensor circuit.
       - A sticking throttle shaft or linkage / cable assembly.
    • Check for proper operation of the crankshaft position (CKP) sensor.
    • Check for proper operation of the MAF sensor (if equipped).
    • Check for proper operation of the MAP sensor (if equipped)

Fuel System Checks

    • Check for proper fuel pump relay operation.
    • Check for proper fuel system pressures. Refer to Fuel System Diagnosis .
    • Check the Gas Distribution Adaptor for proper installation and for leakage.
    • Check for an open natural gas operation (NGO) enable circuit.
    • Check for an accurate fuel indication from the fuel pressure sensor (FPS).