GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Caprice WM 🢒 Engine 🢒 Engine Controls and Fuel - 2.8L, 3.0L, 3.2L, or 3.6L 🢒 Hard Start

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.

Hard Start LPG

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.

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

Fuel System 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.
    • Test for correct operation of the crankshaft position (CKP) sensor.
    • Test for correct operation of the MAP sensor -- if fitted.
    • Test for correct fuel system pressures. Refer to Fuel System Diagnosis.
    • Inspect for correct operation of the LPG fuel injectors. Refer to:
    • Make sure that the manual shut-off valve is fully open.
    • Inspect for restricted LPG lock-offs or filter. Refer to and Fuel Filter Replacement.