GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 S10 Pickup - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Backfire

Checks

Action

Definition: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.

Preliminary Check

Refer to Symptoms .

Ignition System Checks
    • Check the ignition system. Refer to Enhanced Ignition System Diagnosis .
    • Check for crossfire between spark plugs (distributor cap, spark plug wires, and proper routing of the plug wires).

Engine Mechanical Checks
    • Check the engine for the following the items:
       - Engine compression
       - Improper valve timing
       - Intake manifold gaskets, refer to Engine Mechanical.
       - Sticking or leaking valves, refer to Engine Mechanical.
    • Check the EGR operation for being open all the time. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis .
    • Check the intake and exhaust system for casting flash or other restrictions. Refer to Engine Mechanical.

Fuel System Checks
    • Perform a fuel system diagnosis. Refer to Fuel System Diagnosis .
    • Perform a fuel injector balance test. Refer to Fuel Injector Circuit Diagnosis .

Additional Checks
    • Check the EGR gasket for a incorrect or loose fit.
    • Check the EGR Valve operation for being open all the time. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis .