GM Service Manual Online
For 1990-2009 cars only

Fill Line Union (Check Valve) Replacement 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. Object Number: 924841  Size: SH
  5. Disconnect the fill line fitting (10) at the check valve (11) and discard the O-ring.
  6. Remove the check valve (11) from the tee fitting (1) and discard the O-ring.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 924841  Size: SH
  1. Install the check valve (11) to the tee fitting (1) using a NEW O-ring. Lubricate the new O-ring with petroleum jelly or equivalent before installation.
  2. Tighten
    Tighten the check valve to 45 N·m (33 lb ft).

  3. Connect the fill line fitting (10) to the check valve (11) using a NEW O-ring. Lubricate the new O-ring with petroleum jelly or equivalent before installation.
  4. Tighten
    Tighten the fuel line fitting to 45 N·m (33 lb ft).

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

Fill Line Union (Check Valve) Replacement 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. Object Number: 924847  Size: SH
  5. Disconnect the fuel line fitting (4) at the check valve (5) and discard the O-ring.
  6. Remove the check valve (5) from the tee fitting (7) and discard the O-ring.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 924847  Size: SH
  1. Install the check valve (5) to the tee fitting (7) using a NEW O-ring. Lubricate the new O-ring with petroleum jelly or equivalent before installation.
  2. Tighten
    Tighten the fill line fitting to 45 N·m (33 lb ft).

  3. Connect the fill line fitting (4) to the check valve (5) using a NEW O-ring. Lubricate the new O-ring with petroleum jelly or equivalent before installation.
  4. Tighten
    Tighten the fuel line fitting to 45 N·m (33 lb ft).

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