Fuel System

1999 GMC Forward Control 5.7 R, AutomaticSECTION Fuel System
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect the fuel pump relay operation. The fuel pump should turn ON for 2 seconds when you turn ON the ignition.
  2. A faulty in-tank fuel pump check valve allows the fuel in the lines to drain back to the tank after the engine stops. See FUEL SYSTEM DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article.
  3. Verify that both fuel injector fuses are not open. An open fuel injector fuse causes 4 injectors and 4 ignition coils not to operate. Inspect the injector circuits and the ignition coil circuits for an intermittent short to ground. Replace the fuse.
  4. Inspect for incorrect fuel pressure. See FUEL SYSTEM DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article.
  5. Inspect for a restricted fuel filter. See FUEL SYSTEM DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article.
  6. Inspect for a contaminated fuel condition. See ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS (WITH SPECIAL TOOL) or ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL in SYSTEM & COMPONENT TESTING - 5.7L CORVETTE article.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.