GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1997 🢒 Corvette 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 Hard Start

Checks

Action

Definition: Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately dies.

Preliminary
    • Refer to Symptoms , Important Preliminary Checks Before Starting.
    • Check the PCM grounds for being clean, tight and in their proper locations. Refer to PCM wiring diagrams .
    • Search for bulletins.

Sensor/System
    • Check the operation of the Column Lock System. Refer to Body and Accessories/Body Control System .
    • Check the Engine Coolant Temperature (ECT) sensor for being shifted in value. Connect a scan tool. Compare the Engine Coolant Temperature against the Intake Air Temperature (IAT) on a cold engine. The ECT and IAT sensor values should be within ± 3°C (5°F) of each other. If the ECT sensor is out of range with the IAT sensor, check the resistance of the ECT sensor. Refer to Temperature vs Resistance for resistance specifications. Replace the ECT sensor if the resistance is not within the specification. If the sensor is within the specification, repair ECT signal circuit for high resistance.
    • Check the Mass Air Flow sensor installation. A MAF sensor that is incorrectly installed may cause a hard start. Important: The embossed arrows on the MAF sensor indicate the direction of the intake air flow. The arrows must point toward the engine. Install the MAF in the proper direction. Refer to Mass Airflow Sensor Replacement .

Fuel System
    • Check the fuel pump relay operation. The fuel pump should turn ON for 2 seconds when you turn on the ignition. Refer to Fuel Pump Electrical Circuit Diagnosis .
    • A faulty in-tank fuel pump check valve allows the fuel in the lines to drain back to the tank after the engine stops. To check for this condition, refer to Fuel System Diagnosis .
    • Check both injector fuses for being open. An open injector fuse causes four injectors and four ignition coils not to operate. Replace the fuse. Inspect the injector circuits and the ignition coil circuits for an intermittent short to ground.
    • Check for a low fuel pressure condition. Refer to Fuel System Diagnosis .
    • Check for a restricted fuel filter. Refer to Fuel System Diagnosis .
    • Check for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Test .

Ignition System
    • Check both injector fuses for being open. An open injector fuse causes four ignition coils and four injectors not to operate. Replace the fuse. Inspect the ignition coil circuits and the injector circuits for an intermittent short to ground.
    • Check for proper ignition voltage output with spark tester J 26792 . Refer to Electronic Ignition (EI) System Check .
    • Remove the spark plugs and check for the following:
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
    • Refer to Engine Electrical/Spark Plug .
    • Determine the cause of the fouling before replacing the spark plugs if the spark plugs are gas or oil fouled.
    • Check for bare or shorted ignition wires. Refer to Engine Electrical/Spark Plug Wire Harness .
    • Check for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Check .
    • Check the spark plugs for proper heat range. Refer to Engine Electrical/Spark Plug .

Engine Mechanical
    • Excessive oil in combustion chamber-Leaking valve seals. Refer to Engine/Engine Mechanical.
    • Low cylinder compression. Refer to Engine/Engine Mechanical.
    • Combustion chambers for excessive carbon buildup. Clean the chambers using Top engine cleaner. Follow the instructions on the can.
    • For incorrect basic engine parts. Inspect the following:
       - Cylinder heads
       - Camshaft
       - Pistons, etc.

Refer to Engine/Engine Mechanical.