GM Service Manual Online
For 1990-2009 cars only

Evaporative Emission Hose/Pipe Replacement - Chassis Pickup

Removal Procedure

Important: Clean the fuel/EVAP pipe connections and surrounding areas before disconnecting the pipes in order to avoid possible fuel/EVAP system contamination.


    Object Number: 856643  Size: SH
  1. Relieve the fuel system pressure. Refer to Fuel Pressure Relief .
  2. Disconnect the fuel feed and return pipes (1) at the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
  3. Disconnect the evaporative emission (EVAP) canister purge tube (3).
  4. Cap the fuel rail and EVAP pipes in order to prevent possible fuel/EVAP system contamination.
  5. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  6. Remove the fuel hose/pipe bracket nut (2).
  7. Remove the fuel hose/pipe bracket from the bellhousing stud.
  8. Remove the heated oxygen sensor (HO2S) sensor connector from the bracket.

  9. Object Number: 300385  Size: SH
  10. Remove the fuel hose/pipe clip from the bracket on the automatic transmission.
  11. If equipped with 4-wheel drive (4WD), remove the fuel hose/pipe clip from the bracket on the transfer case.
  12. Remove the clip from the bracket on the frame.
  13. Remove the transfer case harness from the clip bracket.
  14. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement .

  15. Object Number: 924296  Size: SH

    Important: The area around the electro-hydraulic control unit (EHCU) MUST be free from loose dirt to prevent contamination of disassembled anti-lock brake system (ABS) components.

  16. Thoroughly wash all contaminants from around the EHCU.
  17. Disconnect the chassis electrical harness connectors from the electronic brake control module (EBCM).

  18. Object Number: 379478  Size: SH

    Important: Make sure that brake lines are tagged and kept in order for proper reassembly.

  19. Disconnect the brake lines from the brake pressure modulator valve (BPMV).
  20. Remove the bolts (4) attaching the EHCU bracket to the frame (5).
  21. Remove the EHCU (1).

  22. Object Number: 878130  Size: SH
  23. If equipped with 4WD, remove the torsion bar bracket. Refer to Torsion Bar Replacement in Front Suspension.
  24. Disconnect the fuel feed and return pipes at the fuel tank. Refer to Plastic Collar Quick Connect Fitting Service .
  25. Cap the fuel pipes at the fuel tank.

  26. Object Number: 878115  Size: SH
  27. If vehicle is a regular cab, remove the fuel feed, EVAP, and return pipe assembly nuts.

  28. Object Number: 878119  Size: SH
  29. If vehicle is a crew or extended cab, remove the fuel feed, EVAP, and return pipe assembly nuts.
  30. Remove the fuel feed, EVAP, and return pipe assembly.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 878119  Size: SH
  1. Install the fuel feed, EVAP, and return pipe assembly.
  2. If vehicle is a crew or extended cab, install the fuel feed, EVAP, and return pipe assembly nuts.
  3. Tighten
    Tighten the nuts to 12 N·m (106 lb in).


    Object Number: 878115  Size: SH
  4. If vehicle is a regular cab, install the fuel feed, EVAP, and return pipe assembly nuts.
  5. Tighten
    Tighten the nuts to 12 N·m (106 lb in).

  6. Remove the caps from the fuel pipes at the fuel tank.

  7. Object Number: 878130  Size: SH
  8. Connect the fuel feed and return pipes at the fuel tank. Refer to Plastic Collar Quick Connect Fitting Service .
  9. If equipped with 4WD, install the torsion bar bracket. Refer to Torsion Bar Replacement in Front Suspension.

  10. Object Number: 379478  Size: SH
  11. Install the EHCU (1).
  12. Install the bolts (4) attaching the EHCU bracket to the frame (5).
  13. Tighten
    Tighten the bolts to 25 N·m (18 lb ft).


    Object Number: 924296  Size: SH
  14. Connect the brake lines to the BPMV.
  15. Tighten
    Tighten the fittings to 25 N·m (18 lb ft).

  16. Connect the chassis electrical harness connectors to the EBCM.

  17. Object Number: 300385  Size: SH
  18. Install the EVAP canister. Refer to Evaporative Emission Canister Replacement .
  19. Install the transfer case harness to the clip bracket.
  20. Install the clip to the bracket on the frame.
  21. If equipped with 4WD, install the fuel hose/pipe clip to the bracket on the transfer case.
  22. Install the fuel hose/pipe clip from the bracket on the automatic transmission.

  23. Object Number: 856643  Size: SH
  24. Install the HO2S sensor connector to the bracket.
  25. Install the fuel hose/pipe bracket to the bellhousing stud.
  26. Install the fuel hose/pipe bracket nut (2).
  27. Tighten
    Tighten the nut to 10 N·m (89 lb in).

  28. Lower the vehicle.
  29. Remove the caps from the fuel rail and EVAP pipes.
  30. Connect the canister purge tube (3).
  31. Connect the fuel feed and return pipes (1) at the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
  32. Install the fuel fill cap.
  33. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  34. Use the following procedure to inspect for leaks:
  35. 25.1. Turn the ignition ON, with the engine OFF, for 2 seconds.
    25.2. Turn the ignition OFF for 10 seconds.
    25.3. Turn the ignition ON, with the engine OFF.
    25.4. Inspect for leaks.

Evaporative Emission Hose/Pipe Replacement - Chassis Cab/Chassis

Removal Procedure

Important: Clean all fuel and evaporative emission (EVAP) pipe connections and surrounding areas before disconnecting the pipes in order to avoid possible fuel/EVAP system contamination.


    Object Number: 856643  Size: SH
  1. Relieve the fuel system pressure. Refer to Fuel Pressure Relief .
  2. Disconnect the fuel feed and return pipes (1) from the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
  3. Disconnect the EVAP canister purge tube (3).
  4. Cap the fuel and EVAP pipes.
  5. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  6. Remove the fuel pipe bracket nut (2).
  7. Remove the fuel pipe bracket from the bellhousing stud.

  8. Object Number: 300385  Size: SH
  9. Remove the fuel hose/pipe clip from the bracket on the transmission.
  10. If equipped with 4-wheel drive (4WD), remove the fuel hose/pipe clip from the bracket on the transfer case.
  11. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement .

  12. Object Number: 878130  Size: SH
  13. Disconnect the fuel feed and return pipes from the fuel tank. Refer to Plastic Collar Quick Connect Fitting Service .
  14. Cap the fuel pipes at the fuel tank.

  15. Object Number: 878123  Size: SH
  16. If vehicle is a regular cab, remove the fuel feed, EVAP, and return pipe assembly nuts.

  17. Object Number: 878126  Size: SH
  18. If vehicle is a extended cab, remove the fuel feed, EVAP, and return pipe assembly nuts.
  19. Remove the fuel feed, EVAP, and return pipe assembly.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 878126  Size: SH
  1. Install the fuel feed, EVAP, and return pipe assembly.
  2. If vehicle is a extended cab, install the fuel feed, EVAP, and return pipe assembly nuts.
  3. Tighten
    Tighten the nuts to 12 N·m (106 lb in).


    Object Number: 878123  Size: SH
  4. If vehicle is a regular cab, install the fuel feed, EVAP, and return pipe assembly nuts.
  5. Tighten
    Tighten the nuts to 12 N·m (106 lb in).

  6. Remove the caps from the fuel pipes at the fuel tank.

  7. Object Number: 878130  Size: SH
  8. Connect the fuel feed and return pipes to the fuel tank. Refer to Plastic Collar Quick Connect Fitting Service .
  9. Install the EVAP canister. Refer to Evaporative Emission Canister Replacement .

  10. Object Number: 300385  Size: SH
  11. If equipped with 4WD, install the fuel hose/pipe clip to the bracket on the transfer case.
  12. Install the fuel hose/pipe clip to the bracket on the transmission.

  13. Object Number: 856643  Size: SH
  14. Install the fuel pipe bracket to the bellhousing stud.
  15. Install the fuel pipe bracket nut (2).
  16. Tighten
    Tighten the nuts to 10 N·m (89 lb in).

  17. Lower the vehicle.
  18. Remove the caps from the fuel and EVAP pipes.
  19. Connect the EVAP canister purge tube (3).
  20. Connect the fuel feed and return pipes (1) to the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
  21. Install the fuel fill cap.
  22. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  23. Use the following procedure in order to inspect for leaks:
  24. 17.1. Turn the ignition ON, with the engine OFF, for 2 seconds.
    17.2. Turn the ignition OFF for 10 seconds.
    17.3. Turn the ignition ON, with the engine OFF.
    17.4. Inspect for fuel leaks.