Rear fuel tank not working at all - and overflowing with fuel!

[GREASE FIRE]

i have never had much luck with the rear tank of my 89 f250. for one thing, it has to be filled by hand because for some reason when i try to fill up at the pump, the pump keeps shutting off every few seconds unless it happens to be a very slow pump.
much worse, however, is that it always seems to run out of fuel long before it is empty. but up until now it always worked a little bit.

now my truck will not drive at all when i select the rear tank. the fuel filter light comes on (and i just changed the fuel filter this week even though i knew that was not the problem) and it shuts down if i do not switch back to front tank. it will not even idle from the rear tank now.

i am getting ready for a long trip - is there any chance someone may know how to fix that? i just yesterday filled the rear tank by hand from 5 gallon jugs and now the fuel is actually overflowing from the top and running all over my driveway! there is no way to drive off the extra fuel or pump it out.

i DO know that the fill cap vent is working because i swapped the front and read ones out and still the same problem.

has anyone else had this problem and actually fixed it? any help would be greatly appreciated!

thanks,
Paul

 

[plywood]

I had the exact same,,,,,,well sort of,,,in my 85 it was overflowing out the rear tank, the only possible explanation was that the fuel selector was sucking fuel out the front tank, and returning it to the rear. So I just plumbed straight to the front tank, no more problems.

 

[hesutton]

Plywood's right, your fuel tank selector vavle if *****. Time for a new one.

Heath

 

[icanfixall]

The above posting hit it on the head. That valve has a motor in it and sometimes crap gets pulled in from a broken off suction valve in the tanks... You probably run out of fuel at 1/4 tank showing on the dash gauge. And it takes around 12 gallons to refill. A piece of 3/8 or 1/2 inch hose will sihpon out all thats in the tank easily...

 

[GREASE FIRE]

thanks for the replies!
just to clear one thing up - the reason the tank was overflowing was because i had just topped it off yesterday, pouring from diesel cans into the tank and i put too much in. i don't think the selector valve is returning fuel from the front tank to the rear but i could certainly be wrong.

fortunately, i have an electric fuel pump on the frame rail so here is what i did:
disconnect the short section of rubber fuel line i put there to connect to the lift pump and put an air chuck from my compressor, blowing back to the rear tank.
at first, 100 psi was not enough to do anything! it was totally blocked somewhere. i tried again, sticking the tip of the chuck into the hose and holding very tightly, this time a whoosh followed by the sound of air bubbles, then my already-overflowing tank overflowed a bit more into the driveway.
i did this a few more times until i was certain the blockage was gone.

i am not sure if the problem is totally solved but i can drive off the rear tank again!
i was able to use the electric lift pump to confirm that fuel flows freely from both tanks now. previously, the electric pump would not draw a single drop of fuel from the rear tank!
who knows what clogged it...but at least for now it works.

thanks!!
paul

 

[Goofyexponent]

If you had a blockage, then the filter light cam on because the IP was drawing a vaccuum. There was no fuel for the lift pump to pull because of a blockage and the IP sensed somethign was wrong when the vaccuum got pulled at the filter housing.

Might be time to take that tank down and give it a goooood cleaning.