GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 45878 Combustible Gas Detector

Removal Procedure

    Caution: Natural gas is highly flammable. In order to reduce the risk of fire and personal injury, keep sparks, flames, and smoking materials away from the vehicle while you perform the Compressed Natural Gas (CNG) fuel system service.

    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. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical in the G/H Van service manual.

  3. Object Number: 859479  Size: SH
  4. Remove the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G/H Van service manual.

  5. Object Number: 893533  Size: SH
  6. Disconnect the CNG crossover fuel line (7, 10) from the fuel rails.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 893533  Size: SH
  1. Connect the CNG fuel crossover line (7, 10) using NEW copper sealing washers.
  2. Tighten
    Tighten the fuel line fittings to 27 N·m (20 lb ft).

  3. Install the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical in the G/H Van service manual.
  4. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings with the J 45878 or an equivalent leak detector.

  5. Object Number: 859479  Size: SH
  6. Install the engine cover. Refer to Engine Cover Replacement in Interior Trim in the G/H Van service manual.