GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Backfire-Intake Manifold


When the engine backfires through the intake manifold, check for the following, as necessary:

Incorrect ignition timing.
Incorrect operation of the choke (carburetor equipped).
Choke setting (initial clearance) too large (carburetor equipped).
Defective Exhaust Gas Recirculation (EGR) valve.
A very lean air/fuel mixture (carburetor equipped).
Fault with the computerized engine control system.