GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC K Pickup - 4WD 🢒 Engine 🢒 Engine Controls - 7.4L 🢒 Hard Start

Checks

Action

Definition: The engine cranks normally, but does not start in a normal amount of time. The engine does eventually run, or may start but immediately dies.

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

Sensor Checks
    • Check the engine coolant temperature (ECT) sensor with the scan tool. Compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit.
    • Inspect the throttle position (TP) sensor. If a sticking throttle shaft or binding linkage causes a high TP sensor voltage, or open throttle indication, the control module will not control the idle. While monitoring the TP sensor voltage, the scan tool should display less than 0.85 volt with the throttle closed.

Fuel System Checks

       Important: A damaged in-tank fuel pump check valve will allow the fuel in the lines to drain back to the tank after the engine stops.

    • Inspect the fuel pump relay for proper operation. The fuel pump should operate for the first 2 seconds when turning ON the ignition. Refer to Fuel Pump Electrical Circuit Diagnosis .
    • Inspect the fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect for water contamination in the fuel.
    • Perform the fuel injector coil test. Refer to Fuel Injector Solenoid Coil Test .
    • Perform the fuel injector balance test. Refer to Fuel Injector Balance Test with Tech 2 .
    • Inspect the fuel pump check valve. Refer to Fuel System Diagnosis .

Ignition System Checks
    • Inspect for the proper ignition voltage output with J 26792 .
    • Inspect the spark plugs for the following conditions:
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
    • Inspect for bare or shorted ignition wires.
    • Inspect for moisture in the distributor cap, if applicable.
    • Inspect for loose ignition coil connections.
    • Inspect for loose ignition control module connections.
    • Inspect for a damaged control module or poor ignition system grounds.
    • Inspect the ignition control (IC) circuit for an open or short to ground. Refer to Enhanced Ignition System Diagnosis .

Engine Mechanical Checks
    • Inspect for the following:
       - Improper valve timing
       - Low compression
       - Refer to Engine Compression Test in Engine Mechanical.
       - Bent pushrods
       -  Valve Rocker Arm and Push Rod Replacement in Engine Mechanical.
       - Worn rocker arms
       -  Valve Rocker Arm and Push Rod Replacement in Engine Mechanical.
       - Broken or weak valve springs
       - Worn camshaft lobes
       - Refer to Camshaft Replacement in Engine Mechanical.
    • Inspect the intake and exhaust manifolds for casting flash. Refer to Intake Manifold Replacement

Additional Check
    • Inspect the idle air control (IAC) operation. Refer to Idle Air Control (IAC) System Diagnosis .
    • Inspect for a restricted exhaust system. Refer to Restricted Exhaust System Check .