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 for incorrect fuel pressure. See FUEL SYSTEM DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article.
  2. Inspect for a restricted fuel filter. See FUEL SYSTEM DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article.
  3. Inspect for 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.
  4. Inspect the fuel injectors. See FUEL INJECTOR COIL TEST in SYSTEM & COMPONENT TESTING - 5.7L CORVETTE article.
  5. Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.
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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.