High Pressure Lock-Off (HPL) Solenoid Replacement

HIGH PRESSURE LOCK-OFF (HPL) SOLENOID REPLACEMENT

TOOLS REQUIRED
- J 43602 HPL Crowfoot - 2.5 inch
- J 45529 Tank Removal Tool
- J 45878 Combustible Gas Detector

REMOVAL PROCEDURE
1. Relieve the CNG fuel system pressure. Refer to Fuel Pressure Relief Procedure.

CAUTION: Do not install this part if you can not completely refill the vehicle with CNG after a repair. Failure to properly leak-check the system after the part replacement may result in serious injury, death, or damage to the vehicle or the part.

2. Disconnect the negative battery cable.

CAUTION: Refer to Battery Disconnect Caution in Service Precautions.

3. Remove the fuel tank cover.




4. Disconnect the high pressure lock-off (HPL) solenoid connectors (5, 7).




5. Vent the fuel pressure from the tank. Refer to Fuel Tank Venting Procedure.
6. Remove the vent hose (6) from the HPL.
7. Remove the line fittings and discard the O-rings.
8. Remove the manual vent tool.




9. With the J 43602 loosen the HPL.Proceed directly to Step 27 for vehicles equipped with the ZW9 option.




10. Disconnect the high pressure regulator fuel inlet line (3).




11. Remove the HPR fuel inlet fitting (6). Capture the filter spring (4), filter (3) and seal (2) that are located behind the inlet fitting.




12. Remove the HPR mounting nut (1).

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.




13. Disconnect the fuel line clips (4) at the lower tank cover mounting bracket.
14. Disconnect the fuel line clips (3) at the tank frame (3).
15. Remove the fuel filter mounting bolts (1).
16. Remove the fuel filter and line assembly from the vehicle.




17. Remove the upper tank cover mounting bracket bolts (3).
18. Remove the upper tank cover mounting bracket (1).




19. Disconnect the HPR coolant hoses from the lower tank cover mounting bracket retainers.
20. Remove the lower tank cover mounting bracket bolts (2).
21. Set aside the mounting bracket assembly in order to gain access to the tank strap retaining nuts.




22. Remove the tank strap retaining nuts (5).
23. Remove the tank strap upper mounting clips (6) and pins (1).
24. Remove the tank straps from the vehicle.




25. Place the J 45529 (1) around the tank (2).
26. Connect the J 45529 (1) to a suitable lifting device and remove the tank from the vehicle.
27. Unthread the HPL from the CNG fuel tank and discard the HPL and O-ring.
28. Inspect the inside of the CNG fuel tank for water, rust, or other contaminants.
29. If necessary, clean the CNG fuel tank. Refer to Fuel Tank Cleaning.

INSTALLATION PROCEDURE
1. Install the NEW O-ring on the HPL.

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.

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. 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. Place the straps around the tank.
7. Install the tank strap upper mounting pins (1) and clips (6).
8. Install the tank strap mounting nuts (5).

NOTE: Refer to Fastener Notice in Service Precautions.


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




9. Tighten the HPL as specified below.

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 for compensation of your torque wrench.

IMPORTANT: Ensure the J 43602 is straight on the 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. Install the HPL port fittings (4, 8) with new O-rings. Lubricate the new O-rings with petroleum jelly.

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

19. On ZW9 vehicles proceed directly to Step 30.




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

22. Attach the HPR coolant hoses to the lower tank cover mounting bracket retainers.




23. Install the HPR mounting nut (1).

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.

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




24. Install the filter spring (4), filter (3) and seal (2) into the HPR inlet port.
25. Install the HPR fuel inlet line fitting (6) with a new O-ring. Lubricate the O-ring with petroleum jelly.

CAUTION: Refer to Compressed Natural Gas (CNG) O-Ring Caution in Service Precautions.

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




26. Install the fuel filter and line assembly.

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. Connect the HPR fuel inlet line (3) with a new O-ring face seal. Lubricate the O-ring face seal using petroleum jelly.

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




29. Install the upper tank cover mounting bracket (1).

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 counter-clockwise until fully seated.
31. Fill the tank and using the J 45878 inspect the HPL O-ring for leaks at each of the following pressures:
1. 3 447 kPa (500 psi)
2. 10 342 kPa (1,500 psi)
3. 20 684 kPa (3,000 psi)

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.

32. Connect the negative battery cable.
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.
35. Install the fuel tank cover. Install the truck body or side panel as required on ZW9 equipped vehicles.