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

Fuel System Checks

    • Inspect for a leaking low pressure lock-off solenoid.
    • Test for proper fuel pump relay operation.
    • Test for proper fuel system pressures. Refer to Fuel System Diagnosis .
    • Inspect the fuel mixer and bonnet for proper installation and for leakage.
    • Test for an open alternative fuels operation (AFO) Signal circuit.
    • Test for an accurate fuel indication from the fuel tank pressure (FTP) sensor.

Sensor Checks

    • Test the ECT sensor for proper operation by performing the following procedures:
        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, with 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 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
    • Test for proper operation of the crankshaft position (CKP) sensor.
    • Test for proper operation of the MAP sensor, if equipped.