GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Cobalt 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Hard Start

Inspection/Test

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 Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .
    • Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views and Engine Controls Schematics .
    • Search for bulletins.
    • Verify that the driver is using the correct starting procedure as described in the owners manual.

Sensor/System
    • Inspect for an engine coolant temperature (ECT) sensor that has shifted in value. Refer to Temperature Versus Resistance .
    • Test for proper operation of the manifold absolute pressure (MAP) sensor. Refer to Altitude Versus Barometric Pressure .
    • Test for proper operation of the throttle position (TP) sensor. Refer to DTC P0106 .

Fuel System
    • Verify there is adequate fuel.
    • Inspect the fuel pump 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. Refer to Fuel System Diagnosis .
    • Test the fuel injectors. Refer to Fuel Injector Diagnosis .
    • Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
    • Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System
    • In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:
       -  Spark Plug Inspection
       -  Spark Plug Replacement
    • Remove spark plugs and inspect for the following:
       - Correct heat range
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
       - Verify that the spark plugs are of the correct type.
    • Inspect for proper ignition voltage output with J 26792 (SA9199Z) Spark Tester.
    • An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool.
    • Determine the cause of the fouling before replacing the spark plugs.
    • Inspect for damaged or misaligned spark plug boots.
    • Inspect the electronic ignition (EI) module for proper ground connection.

Engine Mechanical

Inspect for the following conditions:

    • Excessive oil in combustion chamber or leaking valve seals--Refer to Oil Consumption Diagnosis.
    • Low cylinder compression--Refer to Engine Compression Test.
    • Improper valve timing.
    • Combustion chambers for excessive carbon buildup--Clean the chambers using top engine cleaner. Follow the instructions on the can.
    • Incorrect basic engine parts--Inspect the following:
       - The camshaft--Refer to Camshaft Cleaning and Inspection.
       - The cylinder heads--Refer to Cylinder Head Cleaning and Inspection.
       - The pistons, etc.--Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection.
    • Inspect for excessive crankshaft endplay that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection. This could result in any of the following conditions:
       - A no start
       - A start and stall
       - Erratic performance

Additional
    • Inspect for a restricted exhaust. Refer to Restricted Exhaust.
    • Inspect the air intake ducts for the following:
       - Collapsed
       - Damage
       - Loose
       - Improperly installed
       - Leaking