Fuel Pressure Relieving - At The Fuel Tank (If The Engine Does Not Start)

Fuel Pressure Relieving - At the fuel tank (If the engine does not start)

At the fuel tank (If the engine does not start)

WARNING
Compressed natural gas is flammable and highly explosive. You could be killed or seriously injured if leaking natural gas is ignited.
Stop the engine, and keep heat, sparks, and flames away.

This procedure should be done outside in a well-ventilated area or in a properly equipped CNG shop.

NOTE: This procedure degrades the integrity of the fuel tank. Do it only if you are replacing the fuel tank.

1. Do the battery disconnection procedure. Procedures

2. Raise the vehicle on a lift.

3. Close the manual shut-off valve (A).






4. Slowly loosen the fuel supply line nut (B) going into fuel filter A. Continue to slowly loosen the nut until it is disconnected from fuel filter A.
NOTE:

- The nut may be difficult to turn at first, because of fuel pressure in the line. The fuel eventually escapes with a hiss.

- Always use two wrenches when removing or installing fuel line nuts.

5. Loosen the fuel supply line (C) at the manual shut-off valve, move the end of the line away from fuel filter A, and connect a fuel vent tube (D) (available from the AH special tools department) to the end of the line.

6. Vent the fuel in the line between the fuel tank and the manual shut-off valve by fully opening the manual shut-off valve. The small amount of fuel in the line should vent quickly with a hissing sound. The fuel flow should stop after a few seconds.
- If the fuel flow stops within a few seconds, close the manual shut-off valve, and go to step 7.

- If the fuel flow does not stop within a few seconds, close the manual shut-off valve, then do steps 7 thru 17 of At the fuel tank (If the fuel tank internal valve is stuck open). Fuel Pressure Relieving - At The Fuel Tank (If The Fuel Tank Internal Valve Is Stuck Open)





7. Attach one end of the ground wire (A) (included with the new fuel tank) to the fuel supply line. Route the other end of the ground wire into the vehicle, where it will not interfere with vehicle movement.

8. Lower the vehicle to the ground.






9. Slowly remove the manual lock-down valve (A) from the fuel line side of the fuel tank, and install a manual override vent tool (B) (available from the AH special tools department) in its place.
NOTE: Do not remove the valve (C) from the receptacle side of the fuel tank.

10. With the help of an assistant, push the vehicle outside, near a metal water pipe or a chain-link fence, where the fuel can be safely vented.

11. Attach the other end of the ground wire to the water pipe or to a chain-link fence post buried in the ground. This disperses any static electricity into the ground.

12. Using an Allen wrench, slowly turn the bolt in the manual override vent tool clockwise until the bolt stops.

13. Vent the fuel from the tank by opening the manual shut-off valve. The fuel tank is empty when the hissing is gone, or when fuel cannot be felt coming from the vent pipe. Once the tank is empty, close the manual shut-off valve.
NOTE: Depending on the amount of fuel in the tank, fuel venting can take several minutes, up to a few hours.

14. Remove the manual override vent tool, and reinstall the manual lock-down valve.

15. Reinstall the fuel line to fuel filter A with a new O-ring, then retighten the fuel line at the manual shut-off valve.

16. Do a leak inspection after replacing the fuel tank. Testing and Inspection

17. Do the battery reconnection procedure. Procedures