Ball valve fuel petcock replacement

Larry Trotter

Active Member
Nov 26, 2017
Here’s a way to replace the factory fuel shutoff valve that causes so many people grief. These are the parts you need and why you may need them. The factory fuel valve has a straight 10mm by 1 pitch thread. They seal using a gasket against the tank fuel outlet. Both the valve a seal seem prone to leaks. If you have problems this is a fix that is easy and pretty cheap. To keep it simple all parts are from Granger. You will need at the minimum a 1/8 npt tap, a 1/8 npt ball valve, a 1/8 ntp male hose barb and a little Teflon tape. You may also need a 1/8 ntp close fitting and substitute a female hose barb for the male one.

The 10mm by 1 thread is really close to the he 1/8 27 tpi thread of the pipe fitting. The 10mm straight is 1mm pitch and the pipe is .94mm pitch. Just run the pipe tap into the tank fitting and try to clean up about 4 or 5 threads at the end. If you go too deep you have to fall back to the alternate parts.

Screw in the ball valve with a couple of turns of Teflon tape and tighten it down. Hope to have a little gap to the valve body so the threads make a proper pipe thread seal. Put some Teflon on the barb and put it on and you will be finished. If you can’t get a proper seal then just turn the ball valve around and use the steel close fitting to mate to the tank, they have more threads and will go further into the tank fitting to seal. Then you will have to use the female barb to mate with the valve. My total cost was under $18.00