GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 Envoy - 2WD 🢒 Engine 🢒 Engine Controls - 4.2L 🢒 Fuel Injection Fuel Rail Assembly Replacement

Removal Procedure

    Object Number: 730808 Size: SH
  1. Relieve the fuel system pressure. Refer to Fuel Pressure Relief .
  2. Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  3. Before removal, clean the fuel rail assembly and the cylinder head with a spray type engine cleaner, GM X-30A or equivalent, if necessary. Follow the package instructions. Do not soak the fuel rail in liquid cleaning solvent.
  4. Disconnect the fuel pressure regulator vacuum line.

    5. Object Number: 730718 Size: SH
  5. Disconnect the fuel feed and return pipes (1, 2) from the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
  6. Disconnect the fuel injector harness in-line connector.

    7. Object Number: 730890 Size: SH
  7. Remove the fuel rail attaching bolts.

    8. Notice: 

       • Remove the fuel rail assembly carefully in order to prevent damage to the injector electrical connector terminals and the injector spray tips. Support the fuel rail after the fuel rail is removed in order to avoid damaging the fuel rail components.
       • Cap the fittings and plug the holes when servicing the fuel system in order to prevent dirt and other contaminants from entering open pipes and passages.

  8. Remove the fuel rail assembly.

    9. Object Number: 351185 Size: SH
  9. Remove the injector lower O-ring seal (4) from the spray tip end of each injector (3).
  10. Discard the O-ring seals.
  11. If the fuel rail is not being replaced, go to the Installation Procedure.

Disassembly Procedure
  1. Remove the fuel injectors. Refer to Fuel Injector Replacement .
  2. Remove the fuel pressure regulator. Refer to Fuel Pressure Regulator Replacement .
  3. Remove the fuel injector harness from the fuel rail.

Assembly Procedure
  1. Install the fuel injector harness to the fuel rail.
  2. Install the fuel pressure regulator. Refer to Fuel Pressure Regulator Replacement .
  3. Install the fuel injectors. Refer to Fuel Injector Replacement .

Installation Procedure

    Object Number: 351185 Size: SH
  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. Object Number: 730890 Size: SH
  3. Install the fuel rail assembly.

    4. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  4. Install the fuel rail attaching bolts.

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


    Object Number: 730718 Size: SH
  5. Connect the fuel feed and return pipes (1, 2) to the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
  6. Connect the fuel injector electrical connectors.

    7. Object Number: 730808 Size: SH
  7. Connect the fuel pressure regulator vacuum line.
  8. Install the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  9. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  10. Inspect for leaks.
    11. 10.1. Turn ON the ignition, with the engine OFF for 2 seconds.
    10.2. Turn OFF the ignition for 10 seconds.
    10.3. Turn ON the ignition, with the engine OFF.
    10.4. Inspect for fuel leaks.