Fuel Pressure Relieving - 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)

At the fuel tank (If the fuel tank internal valve is stuck open)

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:

- Do this procedure when the fuel flow does not stop from the tank, even after disconnecting the fuel tank 2P connector.

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

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

2. Start the engine, and let it idle. After a few minutes, the engine stalls.

3. Turn the ignition switch to LOCK (0), and do the battery disconnection procedure. Procedures

4. Raise the vehicle on a lift.






5. Disconnect the fuel supply line (B) from fuel filter A (the line coming from the manual shut-off valve).
NOTE: Always use two wrenches when removing or installing fuel line nuts.

6. 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.






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. 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.

10. 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.

11. Vent the fuel from the tank by opening the manual shut-off valve. Let the fuel vent until the hissing stops. Keep the manual shut-off valve open.
NOTE: Depending on the amount of fuel in the tank, fuel venting can take several minutes, up to a few hours.






12. 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.

13. Using an Allen wrench, slowly turn the bolt in the manual override vent tool clockwise until the bolt stops. This forces the fuel tank internal valve open, ensuring that all fuel is released. Once the tank is empty, close the manual shut-off valve.
NOTE:

- If more fuel vents when you open the fuel tank internal valve, continue to vent the tank until the hissing stops, or when fuel cannot be felt coming from the vent pipe.

- If no fuel vents when you open the fuel tank internal valve, the tank is empty.

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