GM Service Manual Online
For 1990-2009 cars only

Fuel Hose/Pipe Replacement - High Pressure Lock-Off to High Pressure Lock-Off Passenger/Cargo

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. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the G/H Van service manual.
  4. Remove the CNG fuel tank cover. Refer to Fuel Tank Cover Replacement .

  5. Object Number: 893549  Size: SH
  6. Disconnect the fuel line fitting (2, 3) at each high pressure lock-off (HPL) fitting.
  7. Remove the fuel line from the vehicle.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 893549  Size: SH
  1. Connect the CNG fuel line between the high pressure lock-off solenoid fittings (2, 3) using NEW O-rings. Lubricate the new O-rings with petroleum jelly or equivalent before installation.
  2. Tighten
    Tighten the fuel line fittings to 45 N·m (33 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. Install the CNG fuel tank cover. Refer to Fuel Tank Cover Replacement .

Fuel Hose/Pipe Replacement - High Pressure Lock-Off to High Pressure Lock-Off Cutaway

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. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the G/H Van service manual.
  4. Remove the CNG fuel tank cover. Refer to Fuel Tank Cover Replacement .

  5. Object Number: 893543  Size: SH
  6. Disconnect the fuel line fitting (3, 4) at each high pressure lock-off (HPL) fitting.
  7. Remove the fuel line from the vehicle.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 893543  Size: SH
  1. Connect the CNG fuel line between the high pressure lock-off solenoid fittings (3, 4) using NEW O-rings. Lubricate the new O-rings with petroleum jelly or equivalent before installation.
  2. Tighten
    Tighten the fuel line fittings to 45 N·m (33 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. Install the CNG fuel tank cover. Refer to Fuel Tank Cover Replacement .