GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 TrailBlazer - 4WD 🢒 Engine 🢒 Engine Controls and Fuel - 4.2L 🢒 Hard Start

Inspections

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
    • Refer to Important Preliminary Check Before Starting in Symptoms - Engine Controls .
    • Search for bulletins.
    • Make sure the vehicle operator is using the correct starting procedure.

Sensor/System

Monitor 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 high resistance in the coolant sensor circuit.

Fuel System
    • Inspect for a restricted exhaust. Refer to Restricted Exhaust .
    • 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 .
    • Test the fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect for water contamination in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Perform the fuel injector coil test. Refer to Fuel Injector Diagnosis .
    • Perform the fuel injector balance test. Refer to Fuel Injector Diagnosis .
    • Inspect the fuel pump check valve. Refer to Fuel System Diagnosis .

Ignition System
    • Inspect the spark plugs for the following conditions:
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
       - Refer to Spark Plug Inspection .
    • Inspect for loose ignition coil connections.
    • Inspect for loose ignition control module connections.
    • Inspect for a faulty control module or ignition system grounds.

Engine Mechanical
    • Inspect for the following conditions:
    • Improper valve timing
    • Low compression--Refer to Engine Compression Test .
    • Broken or weak valve springs
    • Worn camshaft lobes--Refer to Camshafts Cleaning and Inspection .
    • Proper Cam Phaser operation--Refer to Exhaust Camshaft Position Actuator Description .

Additional

Inspect for a restricted exhaust. Refer to Restricted Exhaust .