I have a 1976 E-250 with a twin tank system and during this summer on several occasions I have had fuel come out of the filler neck and on two separate occasional had it under pressure and spray me with fuel once I removed the fuel cap. It only seems to happen if I leave the van out side and have the sun hitting the filler neck side of the van. Unfortunately it has rewind the custom paint job on it. What sytem is in place to re leaf fuel pressure once it builds in the tank?

 

Are you still using the original gas cap? I think some of those had a vent hole in the cap and some had vent tube. Sounds like it is plugged. There has to be room for the gas to expand in the heat. You could temporarily, loosen the cap when it sits in the sun.

 

Yes, both caps been replaced once I noticed this issue. It did not help. Even with the fuel cap off it will still drain out. I am thinking that one tank is building up pressure more then the other and pushing fuel from one tank to the other and causing it to fill up and then over fill. This there a valve that closes the two tanks off while not in use?

 

I don't think so. My '85 just has a switch changing which tank you are using.