GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 45878 Combustible Gas Detector

Removal Procedure

  1. Relieve the CNG fuel system pressure. Refer to Fuel Pressure Relief .
  2. Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  3. Disconnect the negative battery cable.
  4. Remove the fuel tank cover. Refer to Fuel Tank Cover Replacement .
  5. Remove the trunk trim panel.
  6. Remove the cargo net, the cargo net knobs and the left wheelhouse carpet.

  7. Object Number: 384182  Size: SH
  8. Loosen the fill valve boot clamp and peel back the boot.

  9. Object Number: 296366  Size: SH
  10. Disconnect the fill line (3) at the fill valve (5).

  11. Object Number: 724224  Size: SH
  12. Loosen the clamp at the tank vent boot and peel back the boot to expose the union.
  13. Disconnect the fill line at the union.
  14. Remove the fill line from the vehicle.

Installation Procedure


    Object Number: 724224  Size: SH

    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.

  1. Install the fill line at the union with a new O-ring face seal. Lubricate the O-ring with petroleum jelly or the equivalent.
  2. Tighten
    Tighten the fill line fitting to 37 N·m (27 lb ft).


    Object Number: 296366  Size: SH
  3. Install the fill line (3) at the fill valve (5) with a new O-ring face seal. Lubricate the O-ring with petroleum jelly or the equivalent.
  4. Tighten
    Tighten the fill line fitting to 37 N·m (27 lb ft).

  5. Connect the negative battery cable.
  6. Tighten
    Tighten the bolt to 15 N·m (11 lb ft).

  7. Connect the HPL power electrical connector.
  8. Start the engine. Inspect for CNG fuel leaks at each serviced fitting using the J 45878 .

  9. Object Number: 384182  Size: SH
  10. Slip the vent boot over the fill valve fitting.
  11. Tighten
    Tighten the fill valve boot clamp to 2 N·m (18 lb in).


    Object Number: 724224  Size: SH
  12. Slip the tank vent boot over the union.
  13. Tighten
    Tighten the boot clamp to 2 N·m (18 lb in).

  14. Install the left wheelhouse carpet, the cargo net knobs and the cargo net.
  15. Install the trunk trim panel.
  16. Install the fuel tank cover. Refer to Fuel Tank Cover Replacement .