MTFCA Forum

I have a 1925 ford 4 door with fuel tank under the front seat. I keep having to put fuel in it even though I don't run it that much. I put a rubber gasket between the fuel cap and the tank but that didn't help. The car has no outside leak. The only thing I can think of is the small hole on top of the fuel cap. It has no check valve. Don't see how that little hole could evaporate that much fuel. (About 2 gal a month)

There should be a hole in the fuel cap, it is not a pressurized fuel system. You probably have a small fuel leak somewhere.

It is possible there is a small leak in the sediment bowl, fuel line, or carburetor. If it is parked indoors you might be able to smell it. Try a small tin can under the carburetor and under the sediment bulb and see if you catch a few drops. If they fall on the ground or a floor, they will evaporate and you will not realize there is a leak.
Norm

You could also place a cheap styrofoam cup under the carb and tank outlet.

If the gas leaks into one of them, it'll eat up the strofoam. The gas won't be there, but you'll see evidence of it in the styrofoam.

Drive yer car more, and you'll never miss it.