2002 GMC C3500 HD 8.1 G, StandardFACTORY OEM SERVICE PROCEDURE

Installation Procedure

  1. Lubricate the new lower injector O-ring seals (4) with clean engine oil.
  2. Install the new O-ring seals (4) on the spray tip end of each injector (3).
    Fig 1: Injector & Lower O-Ring Seal
    G01598963Courtesy of GENERAL MOTORS CORP.
  3. Install the fuel rail assembly to the intake manifold.
  4. Apply a 5 mm (0.020 in.) band of GM P/N 12345382 (Canadian P/N 10953489) threadlock or equivalent, to the threads of the fuel rail bolts.
    NOTE: Refer to FASTENER NOTICE in Cautions and Notices.
  5. Install the fuel rail attaching bolts (3).

    Tighten 

    Tighten the bolts to 12 N.m (106 lb in).

    Fig 2: Fuel Rail Assembly & Bolts
    G01598964Courtesy of GENERAL MOTORS CORP.
  6. Connect the fuel pressure regulator vacuum line (1).
    Fig 3: Fuel Pressure Regulator Vacuum Line
    G01598965Courtesy of GENERAL MOTORS CORP.
  7. Connect the fuel feed pipe (1) and the return pipe (2) to the fuel rail.
    Fig 4: Fuel Feed Pipe & Return Pipe
    G01598966Courtesy of GENERAL MOTORS CORP.
  8. Connect the injector electrical connectors.
    • Install each connector on the proper injector in order to ensure correct sequential injector firing order.
    • Rotate the injectors as required in order to avoid stretching the wire harness.
  9. Install the upper engine wire harness bracket.
  10. Install the retainer studs to the upper engine wire harness.

    Tighten 

    Tighten the studs to 10 N.m (89 lb in).

  11. Connect the generator harness connector (1).
  12. Connect the EVAP purge valve harness connector (4).
  13. Connect the throttle position (TP) sensor harness connector (2).
  14. Connect the electronic throttle control (ETC) harness connector (3).
    Fig 5: Generator, EVAP Purge Valve, TP Sensor, & ECT Harness Connectors
    G01598967Courtesy of GENERAL MOTORS CORP.
  15. Tighten the fuel filler cap.
  16. Connect the negative battery cable.
  17. Inspect for leaks using the following procedure:
    1. 17.1. Turn ON the ignition, with the engine OFF for 2 seconds.
    2. 17.2. Turn OFF the ignition for 10 seconds.
    3. 17.3. Turn ON the ignition, with the engine OFF.
    4. 17.4. Inspect for fuel leaks.
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When to See a Mechanic

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

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