GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Sonoma Pickup - 2WD 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 Hard Start

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
    • Check to see if the driver is using the correct starting procedure as described in the owners manual.
    • Refer to Symptoms .
    • Search for service bulletins.

Sensor/System
    • Check the Engine Coolant Temperature (ECT) sensor for being shifted in value. Install a scan tool and compare the Engine Coolant Temperature with the Intake Air Temperature (IAT) sensor on a cold engine. The ECT and IAT should be within ± 3°C (5°F) of each other. Check the resistance of the ECT sensor if the temperature is out of range with the IAT sensor. Refer to Temperature Versus Resistance . If the ECT sensor resistance is not within the specification, refer to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage or DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage .
    • Check for proper operation of the MAP sensor . Refer to Manifold Absolute Pressure Sensor Output Diagnosis .
    • Check for proper operation of the TP sensor.
    • Check for proper operation of the IAC valve.

Fuel System
    • Check for adequate fuel level.
    • Check the fuel pump relay circuit for proper operation. Refer to Fuel Pump Electrical Circuit Diagnosis
    • Check for incorrect fuel pressure. Refer to Fuel System Diagnosis
    • Check the fuel injectors.
       - Refer to Fuel Injector Balance Test .
    • Check for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check the in-tank fuel pump check valve. The in-tank fuel pump check valve may be malfunctioning, causing the fuel in the lines to drain back to the fuel tank after the engine is stopped.
        Refer to Fuel System Diagnosis .

Ignition System
    • Check for proper ignition voltage output with the spark tester J 26792 or equivalent.
    • Check the spark plugs for the following conditions:
       - Check for wet or fuel fouled spark plugs.
       - Check for cracks on the spark plugs.
       - Check for wear.
       - Check for improper spark plug gap.
       - Check for burned electrodes or heavy deposits.
    • If the spark plugs are fuel or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
    • Check the Ignition Control Module (ICM) for proper ground connection.
    • Check the ignition coils for cracks or carbon tracking.
    • Check the spark plug wires for proper resistance and condition.

Engine Mechanical
    • Check the engine for the following engine mechanical problems:
       - Check for low compression.
       - Check for leaking cylinder head gasket.
       - Check for a worn or a incorrect camshaft.
    • Refer to the Engine Mechanical Portion of the service manual.

Additional Checks

If all procedures have been completed and no malfunctions have not been found, review and inspect the following items:

    • Visually and physically inspect all electrical connections within the suspected circuit and/or systems.
    • Check scan tool data.