u/vertofu

I have a 1979 Chevy P30 step van with a 350 cu V8 converted to propane. The system includes a vacuum fuel lockoff valve and an IMPCO vaporizer.

I have the tank empty while I paint it and fix its leaking pressure relief valve. If possible, I'd like to leak check the fuel system before refilling with liquid. If I introduce propane vapor from a 20lb BBQ tank, the lockoff valve leaks. Does this mean it will also leak when exposed to liquid propane?

Also, if anyone can recommend a better place to ask, that would be much appreciated.