Backfire. GMC Truck GMC K Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Sierra - 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

-	Manifold gaskets

-	Sticking or leaking valves

•	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 fresh air entering the exhaust upstream of the catalytic converter or restrictions.

Fuel System Checks

•	Check the fuel system performance. Refer to Fuel System Diagnosis .

•	Perform the fuel injector balance test. Refer to Fuel Injector Balance Test with Tech 2 .

Additional Checks

•	Check the EGR gasket for a faulty or loose fit.

•	Check the AIR System for proper operation (If applicable).