Civic GX Sedan L4-1.6L CNG (1998)
4. Connect a ground wire to the fuel line to eliminate any static electricity.
5. Disconnect the fuel supply pipe from the pressure regulator. Be careful not the lose the O-rings.
6. Connect the vent tube to the fuel supply pipe.
7. Secure the other end of the vent tube to the highest possible location.
8. Remove the fuel pipe duct, and slowly remove the manual lock-down valve. Install the manual override vent tool in its place.
9. Slowly turn the tool's Alien bolt clockwise until it stops. This opens the line between the fuel tank and the manual shut-off valve.
10. Open the manual shut-off valve so fuel can vent from the fuel tank. The fuel tank is empty when the hissing sound goes away.