GM Service Manual Online
For 1990-2009 cars only

Draining Procedure

    Caution: The Compressed Natural Gas (CNG) system operates at pressures up to 24820 kpa (3600 psi). Relieve the CNG fuel system pressure before servicing CNG fuel system components in order to reduce the risk of fire and personal injury.

  1. Relieve the CNG fuel system pressure. Refer to Fuel Pressure Relief .
  2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the J Platform Service Manual.

  3. Object Number: 802264  Size: SH
  4. Slowly loosen the in-line CNG filter drain plug allowing any remaining CNG fuel pressure to escape.
  5. Remove the drain fitting and capture any fluids. Dispose of the fluid in a safe manner.
  6. Install the drain plug using a new O-ring. Refer to Maintenance Items in General Information for the correct O-ring part number. Lubricate the O-ring with petroleum jelly.
  7. Tighten
    Tighten the drain plug to 48 N·m (35 lb ft).

Removal Procedure

  1. Relieve the CNG fuel system pressure. Refer to Fuel Pressure Relief .
  2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the J Platform Service Manual.

  3. Object Number: 802270  Size: SH
  4. Loosen the in-line CNG filter housing.
  5. Unthread and remove the housing.

  6. Object Number: 802266  Size: SH
  7. Remove the filter element (2) from the in-line CNG filter assembly (1) using a pulling and twisting motion.
  8. Wipe out any oil or fluid residue from the inside of the filter housing.

Installation Procedure


    Object Number: 802266  Size: SH
  1. Push the filter element (2) onto the in-line CNG filter assembly (1).

  2. Object Number: 802267  Size: SH
  3. Install the filter housing into the in-line CNG filter assembly using a new O-ring. Lubricate the O-ring with petroleum jelly before installation.
  4. Tighten
    Tighten the filter housing to 54 N·m (40 lb ft).

  5. Cycle the ignition several times in order to build CNG fuel pressure.
  6. Inspect for fuel system leaks at all serviced fittings.