92 ford f-150 gas leak

My 92 ford f-150 has two gas tanks, and the front tank leaks out of the cap when i park after driving. The leak doesn't happen immediately, but it takes place maybe an hour after stopping. Does someone know what the problem is and how to fix it?

It may be that the vent for the REAR tank is plugged, so as pressure in system builds, it cannot escape from the rear tank, only the front. So, fuel is forced by pressure into the front tank (since it can vent) thereby overfilling it causing a spill.

If the rear in-tank pump has been replaced, I would check for any pinched or crimped vent hoses to the rear tank. If you are not careful when re-installing the tank, they can easily get trapped and pinched off.

I have a similar problem with fuel coming out of the cap on my '80 F100. It only has one tank, and the overflow happens when i'm pumping gas. It's a real pain in the.... As long as I pump fuel barely squeezing the handle, it's alright (but it takes forever!). Soon as i pull that handle all the way I hear fuel rising then a bunch of fuel comes out. Is this caused by a venting problem too? or is it something else?

It is a recall on the switch that allows the tanks to switch which tank is pumping. if you only fill up the front tank no prob. but it you fill up the rear it will end up in the front tank. I had mine replaced when i got the notice in 2001 or earlier.