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Home >> GMC >> 2001 >> C3500 HD 8.1 G, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 8.1L - Repair Instructions >> Repair Instructions >> Fuel Injection Fuel Rail Assembly Replacement >> Installation Procedure
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Installation Procedure

    Fig 1: View Of Fuel Injector, Clip & O-Rings
    GM351185Courtesy of GENERAL MOTORS COMPANY
  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).
    3. Fig 2: View Of Fuel Rail Assembly
    GM665443Courtesy of GENERAL MOTORS COMPANY
  3. Install the fuel rail assembly (1) to the intake manifold.
  4. Apply a 5 mm (0.020 in) band of GM P/N 12345382 threadlock, or equivalent, to the threads of the fuel rail bolts.

    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).

    6. Fig 3: View Of Fuel Pressure Regulator Vacuum Line
    GM665447Courtesy of GENERAL MOTORS COMPANY
  6. Connect the fuel pressure regulator vacuum line (1).
    7. Fig 4: View Of Rear Of Engine Fuel Pipe Connections
    GM300360Courtesy of GENERAL MOTORS COMPANY
  7. Connect the fuel feed and return pipes (1, 2) to the fuel rail.
  8. Connect the injector electrical connectors (4).
    • 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 Secondary Air Injection (AIR) crossover pipe if applicable. Refer to Secondary Air Injection Crossover Pipe/Hose Replacement .
    10. Fig 5: View Of Front Of Engine
    GM665449Courtesy of GENERAL MOTORS COMPANY
  10. Install the upper engine wire harness bracket .
  11. Install the retainer studs to the upper engine wire harness.

    Tighten 

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

    12. Fig 6: View Of Front Of Engine
    GM665449Courtesy of GENERAL MOTORS COMPANY
  12. Reconnect the generator harness connector (1).
  13. Reconnect the (EVAP) canister purge valve harness connector (4).
  14. Reconnect the throttle position (TP) sensor harness connector (2).
  15. Reconnect the electronic throttle control (ETC) harness connector (3).
    16. Fig 7: Intake Manifold Sight Shield, Bolts & Retainer
    GM665445Courtesy of GENERAL MOTORS COMPANY
  16. Install the engine sight shield mounting bracket blots and nuts.

    Tighten 

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

  17. Tighten the fuel filler cap.
  18. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection (Auxiliary Battery) , Battery Negative Cable Disconnection and Connection (Single Battery) in Engine Electrical.
  19. Inspect for leaks using the following procedure:
    1. Turn ON the ignition, with the engine OFF, for 2 seconds.
    2. Turn OFF the ignition for 10 seconds.
    3. Turn ON the ignition, with the engine OFF.
    4. Inspect for fuel leaks.
  20. Install the engine sight shield.

    Tighten 

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

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