GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2007 🢒 H3 🢒 Engine 🢒 Engine Controls and Fuel - 3.7L 🢒 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 Beginning in Symptoms - Engine Controls .
    • Inspect the powertrain control module (PCM) 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 .

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
       - Spark plugs are of the correct type.
    • Inspect for proper secondary ignition voltage output with J 26792 HEI Spark Tester .
    • An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gauge gap tool.
    • If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs.
    • Inspect for damaged or misaligned spark plug boots.

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.
    • Broken or worn valve springs
    • Combustion chambers for excessive carbon buildup--Clean the chambers using top engine cleaner. Follow the instructions on the can.
    • Proper camshaft actuator system operation--Refer to Camshaft Actuator System Description .
    • Incorrect, worn, or damaged basic engine parts--Inspect the following:
       - The camshaft--Refer to Camshafts 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 .

Additional
    • Inspect for a restricted exhaust. Refer to Restricted Exhaust .
    • Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed, or leaking.