LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1168 (Engine Controls - 6.0L - Alternative Fuels (Introduction)) >> Repair Instructions >> High Pressure Lock-Off (HPL) Solenoid Replacement >> Installation Procedure

Installation Procedure

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
    CAUTION: Natural gas is stored under high pressure. If a leak occurs, the high pressure could cause a personal injury. In order to prevent Compressed Natural Gas (CNG) fuel leaks, always replace the CNG fuel system O-rings during service.
  1. Install the NEW O-ring on the HPL.
  2. Lubricate the O-ring with petroleum jelly.
  3. Ensure that the O-ring mating surface of the tank is clean and free of debris or damage.
  4. Install the HPL in the tank and tighten hand-tight.

    Do not install the fuel line fittings.

    Proceed directly to Step 9 for vehicles equipped with the ZW9 option.

    5. Fig 1: Positioning CNG Tank Support Harness
    GM763748Courtesy of GENERAL MOTORS CORP.
  5. Lower the fuel tank (2) into the tank mounting frame ensuring that the high pressure lock-off solenoid is properly oriented to the fuel line.
    6. Fig 2: Identifying Tank Strap Retaining Components
    GM763211Courtesy of GENERAL MOTORS CORP.
  6. Place the straps around the tank.
  7. Install the tank strap upper mounting pins (1) and clips (6).
    8. NOTE: Refer to Fastener Notice in Cautions and Notices.
  8. Install the tank strap mounting nuts (5).

    Tighten:  Tighten the tank strap mounting bolts to 47 N.m (35 lb ft).

    9. Fig 3: Tightening HPL
    GM491673Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: Ensure the J 43602  is straight on the torque wrench. See Special Tools and Equipment .
  9. Tighten the HPL as specified below.

    Tighten:  Tighten the HPL to a nominal torque of 305 N.m (225 lb ft) at 0 degrees. You must compensate for the torque wrench and the HPL crowfoot offset. Refer to the formula below for compensation of your torque wrench.

  10. To obtain your dial reading perform the following procedure:
    • Multiply your torque wrench length in inches by 305 (225).

      18 inch torque wrench example: 18 X 305 = 5490.

    • Add 3 to the length of your torque wrench.

      18 inch torque wrench example: 18 + 3 = 21.

    • Divide the first value obtained by the second value obtained. The result indicates the amount of torque your wrench should tighten the HPL to.

      18 inch torque wrench example: 5490 divided by 21 = 261.4.

      For an 18 inch long torque wrench tighten the HPL to 261.4 N.m.

    11. Fig 4: Identifying HPL Line Fittings
    GM763013Courtesy of GENERAL MOTORS CORP.
  11. Install the HPL port fittings (4, 8) with new O-rings. Lubricate the new O-rings with petroleum jelly.

    Tighten:  Tighten the fitting to 48 N.m (35 lb ft).

  12. Install the fuel tank pressure (FTP) sensor (2) with a new O-ring. Lubricate the O-ring with petroleum jelly.

    Tighten:  Tighten the sensor to 27 N.m (20 lb ft).

  13. Connect the FTP sensor connector (1).
  14. Connect the HPL solenoid connectors (5, 7).
    15. Fig 5: Identifying HPL Line Fittings And Fuel Lines
    GM1489671Courtesy of GENERAL MOTORS CORP.
  15. Ensure that the HPL line fittings and the fuel lines are properly oriented. On ZW9 vehicles the FTP sensor should be at the 12 O'clock position.
  16. Loosen the tank strap bolts and rotate the tank as required in order to align the fuel line and fittings.

    Tighten:  Tighten the tank strap mounting bolts to 47 N.m (35 lb ft).

  17. Connect the tee fitting (3) to the HPL fitting (2) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. On ZW9 vehicles connect the fuel outlet line to the fitting.

    Tighten:  Tighten the line fitting to 37 N.m (27 lb ft).

  18. Connect the fuel line fitting (4) to the tee fitting with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. On ZW9 vehicles connect the fuel inlet line to the fitting.

    Tighten:  Tighten the line fitting to 37 N.m (27 lb ft).

  19. On ZW9 vehicles proceed directly to Step 30.
    20. Fig 6: Locating Lower Tank Cover Mounting Bracket Bolts
    GM794990Courtesy of GENERAL MOTORS CORP.
  20. Slide the lower tank cover mounting bracket over the HPR and into position.
  21. Install the lower tank cover mounting bracket and bolts (2).

    Tighten:  Tighten the bolts to 50 N.m (37 lb ft).

  22. Attach the HPR coolant hoses to the lower tank cover mounting bracket retainers.
    23. Fig 7: Identifying High Pressure Regulator (HPR) Components
    GM757008Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: Do not hold the HPR using the HPR cover hex flange. As required wedge a wrench between the HPR and the tank frame in order to keep the HPR from spinning in the bracket.
  23. Install the HPR mounting nut (1).

    Tighten:  Tighten the nut to 54 N.m (40 lb ft).

    24. Fig 8: Identifying High Pressure Regulator (HPR) Inlet Fitting Components
    GM327075Courtesy of GENERAL MOTORS CORP.
  24. Install the filter spring (4), filter (3) and seal (2) into the HPR inlet port.
    25. CAUTION: Refer to Compressed Natural Gas (CNG) O-Ring Caution in Cautions and Notices.
  25. Install the HPR fuel inlet line fitting (6) with a new O-ring. Lubricate the O-ring with petroleum jelly.

    Tighten:  Tighten the fuel line fitting to 48 N.m (35 lb ft).

    26. Fig 9: Fuel Tank Components
    GM794992Courtesy of GENERAL MOTORS CORP.
  26. Install the fuel filter and line assembly.

    Tighten:  Tighten the bolts (1) to 27 N.m (20 lb ft).

  27. Fasten the fuel line at the lower tank cover mounting bracket (4) and the tank strap (3).
    28. Fig 10: Identifying High Pressure Regulator (HPR) Fuel Inlet Line
    GM762011Courtesy of GENERAL MOTORS CORP.
  28. Connect the HPR fuel inlet line (3) with a new O-ring face seal. Lubricate the O-ring face seal using petroleum jelly.

    Tighten:  Tighten the fitting to 37 N.m (27 lb ft).

    29. Fig 11: Locating Upper Tank Cover Mounting Bracket Bolts
    GM763174Courtesy of GENERAL MOTORS CORP.
  29. Install the upper tank cover mounting bracket (1).

    Tighten:  Tighten the bolts to 8 N.m (71 lb in).

  30. Ensure that the HPL manual shut-off valve is open by turning the Allen screw valve counterclockwise until fully seated.
    31. CAUTION: The high pressure lock-off solenoid seal is more likely to leak at a lower fuel pressure. Always perform the fuel leak procedure exactly as specified. Failure to follow the proper procedures may result in serious injury or damage to the vehicle or part.
  31. Fill the tank and using the J 45878  inspect the HPL O-ring for leaks at each of the following pressures. See Special Tools and Equipment .
    1. 3447 kPa (500 psi)
    2. 10,342 kPa (1,500 psi)
    3. 20,684 kPa (3,000 psi)
  32. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
  33. Prime the CNG fuel system by cycling the ignition ON and OFF several times.
  34. Start the engine and use the J 45878  in order to inspect for CNG fuel system leaks at each serviced fitting. See Special Tools and Equipment .
  35. Install the fuel tank cover. Refer to Fuel Tank Cover Replacement . Install the truck body or side panel as required on ZW9 equipped vehicles.
scientia non olet · About LEMON Manuals