Here is one that will not be in the owners manual.
This Ford F150 has dual gas tanks. I have had other vehicles that
have dual tanks and there is normally an electric fuel switch-valve.
They were always under the vehicle, had a hose from each gas tank
hooked to it, and the 3rd hose that goes to the engine. They seemed
to always go bad every few years.
This truck does not have one of those switch-valves. It has dual
tanks but does not have any visible switch-valve under the floor. I
carefully looked. There are two hoses from each tank that connect in
a TEE. (gas hose and vapor return).
At first I thought someone removed that valve and installed these
tees, but it looks original.
There is a switch on the dash to switch from front to rear tanks. The
front one works, but when I switch to the rear one, the engine dies.
What in the heck is that switch switching?