GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2004 🢒 VUE - AWD 🢒 Engine 🢒 Engine Controls - 3.5L (L66) 🢒 Hard Start

Hard Start

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 Symptoms - Engine Controls .
    • Check that the driver is using the correct starting procedure.

Sensor Checks
    • Check the engine coolant temperature (ECT) sensor using a scan tool to compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5°C (9°F) more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or in the sensor. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor .
    • Check the crankshaft position (CKP) sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed are displayed, the engine reference signal is not stable enough for the engine to start and run properly.

Fuel System Checks
    • Check the fuel pump relay for correct operation. Observe the fuel pump relay operation on a scan tool while cranking the engine.
    • Check the fuel pressure. Refer to Fuel System Diagnosis .
    • Check for water contamination in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check the fuel pump check valve. A faulty fuel pump check valve will allow the fuel in the lines to drain back into the tank after stopping the engine. This condition is especially troublesome on hot soak restarts. In order to check for this condition perform the following steps:
        1. Turn OFF the ignition.
        2. Install the fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
        3. Pressurize the fuel rail by turning the ignition key ON and OFF a few times.
        4. Turn the ignition key ON and observe the fuel pressure. The fuel pressure has to remain more than 275 kPa (40 psi) for at least 5 minutes.

Ignition System Checks
    • Check for the proper secondary voltage output with a J 26792 Spark Tester or equivalent. Refer to Electronic Ignition (EI) System Diagnosis .
    • Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection .
    • Check for bare or shorted ignition system wiring.
    • Check for loose ignition coil connections.

Additional Checks
    • An incorrect TP learned value can cause a hard start condition and needs to be reset. Before resetting the TP learned value, inspect for excess deposits in the throttle body and clean as necessary. Refer to Throttle Body Inspection and Cleaning and Scan Tool Output Controls .
    • Check the Service Bulletins for any updates.