Originally Posted by billt
This was one of the main reasons Ford got away from a 2 tank system with their F-150's. Mine is a 1991 that has 2 tanks. It had a recall a year or so after I bought it, because some vehicles had defective solenoids in the tank switching mechanism. When I brought it in, I got to talking to one of the mechanics who did the recall on my truck.
He told me Ford was planning to do away with a 2 tank fuel system. The biggest reason was because many people were running one tank dry before switching. This was the cause of many cooked fuel pumps that Ford was forced to replace under warranty. It wasn't long after that they did disappear in favor of a single tank system.
It was for the best anyway.
One centrally located pill-shaped tank set within and across the entire vehicle frame is actually safer and more structurally sound than two separate tanks placed on either side where they are more exposed to impact and can be crunched together like a pair of coconuts.
A large tank offers more space to put more strengthening patterns and provides fewer points of failure in a crash. Plus, a single tank is able to balance itself to the vehicle better than two tanks can.