GM Service Manual Online
For 1990-2009 cars only

Hard Start Petrol

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 - Engine Controls).
    • Make sure the vehicle operator is using the correct starting procedure.

Fuel System Checks

    • Test for correct fuel relay operation.
    • Test for correct fuel system pressures. Refer to Fuel System Diagnosis.

Sensor Checks

    • Test the ECT sensor for correct 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.
    • Test the TP sensor for correct 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
    • Test for correct operation of the crankshaft position (CKP) sensor.
    • Test for correct operation of the MAP sensor - if equipped.