Dual tank Problem

[srkr]

I have a 81 f100 with dual tanks. Had them both replaced cuz the truck sat so long. When the weather warms up fuel runs out of the front tank where the gas cap goes. When I unscrew the rear tank gas cap I hear a woosh and the front stops over=flowing. Does this make sense? Should there be some kind of air pressure release on the front tank?

Also, the gauges will read the level of fuel from the front and rear tanks but, will take fuel from the rear tank, even after switching, only the rear.

Heres a pic of the truck

Shane

 

[tomtoc]

i assume what you have is similar to the 92-96 trucks.

try searching for "crossflow". i think it's pumping from the back to the front, overflowing the front tank

EDIT: welcome to the forum, and sweet truck

 

[srkr]

The trucks not running. Does that matter?

 

[tomtoc]

seems like that should only happen when it's running to be, but one of the experts should be along to give you a better answer

 

[srkr]

Bump

 

[blacksnapon]

Sounds like a switching issue. Thats the only place where both tanks have a common connection.