High Pressure Regulator (HPR) Replacement

HIGH PRESSURE REGULATOR (HPR) REPLACEMENT

TOOLS REQUIRED
J 45878 Combustible Gas Detector

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

CAUTION:
- Refer to Compressed Natural Gas (CNG) Flammability Caution in Service Precautions.
- Refer to Compressed Natural Gas (CNG) Fuel Pressure Relief Caution in Service Precautions.

2. Disconnect the negative battery cable.

CAUTION: Refer to Battery Disconnect Caution in Service Precautions.




3. Remove the tank cover (2).




4. Partially drain the coolant or pinch off the high pressure regulator (HPR) coolant hoses (3, 5). Refer to Draining and Filling Cooling System (w/RPO HP2) Draining and Filling Cooling System (w/o RPO HP2) in Cooling System in the C/K Pickup Service Data.
5. Loosen the hose clamps enough to move the clamps (2, 6) away from the HPR coolant fittings.
6. Disconnect the HPR coolant hoses (3, 5) from the HPR.
7. Disconnect the HPR fuel inlet line (9).
8. Disconnect the HPR fuel outlet line (4).
9. Remove the HPR fuel inlet line fitting from the HPR. Capture the filter spring, filter and seal that are located behind the fuel inlet line fitting.
10. 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.

11. Remove the HPR from the mounting bracket.

DISASSEMBLY PROCEDURE
Use the following procedure if any HPR fittings require replacement:




1. Remove the coolant fittings (2, 5).
2. Remove the pressure relief device (3).
3. Remove the fuel outlet fitting (4).




4. Remove the filter spring (4).
5. Remove the filter (3).
6. Remove the seal (2).

ASSEMBLY PROCEDURE




1. Install the filter seal (2).
2. Install the filter (3).
3. Install the filter spring (4).




4. Install the fuel outlet fitting (4).

IMPORTANT: Prior to installation, apply pipe thread sealant with Teflon(R) to the threads of the following:
- Fuel outlet fitting (4)
- Pressure relief device (3)
- Coolant fittings (2, 5)

Tighten the fuel outlet fitting hand tight plus one to three turns as required to seal and properly align the fitting.

5. Install the pressure relief device (3).

Tighten the pressure relief device hand tight plus one to three turns as required to seal the fitting.

6. Install the coolant fittings (2, 5).

Tighten the coolant fittings hand tight plus one to three turns as required to seal and properly align the fitting.

INSTALLATION PROCEDURE




1. Install the HPR assembly (8) to the mounting frame (7).
2. Install the HPR mounting nut (1).

NOTE: Refer to Fastener Notice in Service Precautions.

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).

3. Connect the HPR fuel outlet line (4) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly.

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

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

4. Install the fuel inlet line fitting using a new O-ring. Lubricate the O-ring with petroleum jelly.

IMPORTANT: Prior to installing the fuel inlet line fitting confirm that the fuel filter, spring and seal are properly seated in the HPR.

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

5. Connect the HPR fuel inlet line (9) to the HPR fitting.

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

6. Connect the HPR coolant hoses (3, 5) to the HPR.
7. Tighten the coolant hose clamp (6) ensuring that the clamp fastens the hose to the HPR fitting.
8. Remove the coolant hose pinch pliers if used.
9. Install the negative battery cable.

CAUTION: Refer to Battery Disconnect Caution in Service Precautions.

10. Fill the cooling system. Refer to Draining and Filling Cooling System (w/RPO HP2) Draining and Filling Cooling System (w/o RPO HP2) in Cooling System in the C/K Pickup Service Data.
11. Inspect the cooling system for leaks. Refer to Loss of Coolant in Cooling System in the C/K Pickup Service Data.
12. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector.




13. Install the tank cover (2).