ok, my truck runs fine but when the back tank reads 1/2 tank on the gauge the truck will stall and die like it is starved for fuel. it seems like the truck is only running off of the top half of the tank. when i dropped the tank this morning it still had aprox 7 gallons still inside. i pulled out the sending unit and tested the float and it seems to be reading as it should as far as full and empty. i did find a small black plastic hose and a screen in the bottom of the tank. but they don't seem to go together. i've called just about every parts store in town including the ford parts counter at the dealership and no one could help me. any ideas?

 

sounds like a pickup tube, i am positive that they do go together but how i cant say for sure. The screen should lay on the bottom and feeds off the tank like a bottom feeder. The tube conencts to the pickup unit and supplies fuel. the splashing around caused by driving gave it enough to sound starved but not enough to run. If the auto parts store didnt know what you meant, you might just take it in to them or tell them you need the unit that sucks up the fuel and keep it real simple. sounds like you have a dork auto parts guy on your hands.

 

Just take a piece of fuel line about 6" long and slip it over the pickup tube.
Then put a fuel line clamp over the splice to keep it there.
Now cut a V in the end of the fuel line so it will not suck up against the side or bottom of the tank and shut the fuel off.

Put everything back together and enjoy that last 7 gallons of fuel in the tank before you have to fill up again.

Very common problem.