Do the gas tanks have an over flow valve? I filled the tank completely full left and got a call 30 min later about gas leaking from under the truck.
You have a leakey shut off valve more than likely. Crawl under there and look in the middle of the floor where the gas line drops down from the tank and comes to an elbow. That elbow should have a small spinner handle on it. There will probably be gas dring from it. Otherwise, the gasket between the sending unit and tank is rotted out and the gas has run out the top, down the tank and is draining through the floor, making your interior into a bomb. Both are fairly common occurances in these trucks.
I had this happen too, I don't have a shut off anymore under my truck, just the nipple and a flex line that goes to the ss line, but ol chebby is right, they did have them. what i had done, was fill up on a warm sunny day. The gas from the station is underground and is nice and cool. I drove about 30 miles, and parked my truck on an slope. I ended up having to move it. I had fuel running back out the filler or vent. Just a bit. But as the gas warms up it expands, thus spilling back out. So now what I do is not fill it so full, haven't had a problem since.
Fuel Spillage FWIW ; Gasoline expends about 10 % when it gets really hot in the sun so never top it off unless you're about to hit the Highway .
