My truck seems to have a problem, it transfers the fuel from the front tank to the rear, while the switch it on the front, but doesn't seem to be able to run on the rear tank. Is this common, what is the fix? Need to get it running quick and cheap, as it is primary transport, and i need to get feed for the horses tomorrow

 

Very common problem. The fix depends on what year truck you have.

 

hey I have the same problem with mine. what I found out is the fuel selector. this is not an electrical solenoid but a pressure valve type. it has o-rings on the valves that swell up. as a temporary fix, i removed the o-rings. my plan is to replace this type of selector valve with a electrical solenoid type.
i would suggest to check the low pressure pump in your rear tank.

 

hi, i am having the same problem but my truck is transferring the fuel from the rear to the front. i had just changed my rear tank because it leaked and my pump went on the front tank and the cheaper fix was the tank but now i have this problem. i just lost about $50 of gas on the highway because once my front tank filled up it spilled out. how does the o rings affect this, and can these o-rings be changed.

 

Sounds like you have a 1990 or newer truck so I would say you have a bad rear fuel pump (FDM).

 

As you were told in your own Thread you have a bad front pump (FDM).
There are no "O" rings in it to change.

 

That is true for a 1989 and older truck.

 

sorry to hi-jack someone elses thread. i posted hear before starting my own, but thanks for the quick replies.

 

Thanks for your reply. Went in got feed, ran out of fuel in the front and had to siphon 5 times but horses are now happy. The Ford Dealer says the Cask for clunkers program erased any recalls on the truck (1987), the local boneyard will sell me both tank pumps and the pressure tank valve and guarantee them for $125, is better than the ford only parts which would be near 400 and the pumps about $125 each. Not cheap and a real nuisance to repair but beats the price tag the ford garage quoted. Good luck!! Wanted to put manuel valve but am told that won't work with this system. Me I wish an old 50 with a flathead 110 would run on unlead.

 

Subford, I got the same problem. I just replaced the front FDM, when running from the front it doesn't transfer, but when running from the rear it zips it on through to the front? Really don't want to change the front again.
Jeff

 

I would say the front one is bad or more than likely it is missing both valves.
I have heard of one brand of the FDM had left the valves out of a lot of the FDM they made. This would work fine for a one tank truck, van or RV but not for a two tank truck.
When you replace it get a different brand. You should not be able to blow bad into it from either tube when you buy it.
Note that a bad fuel pressure regulator that lets the pressure go too high will blow out the valve in the non running tank also.

 

Thanks Bill for the info. 80 here today, took the new Bosch fdm out. Just got the tank back in with a new Ford FDM($$$$), works fine when the front tank is selected, when the rear tank is selected, fills the front, but not very fast. Haven't checked the return lines at the rear tank yet, or the pressure on the rail yet. The rear has been in for 16 years. Guess I can use the front tank until I get more $$$ for the rear one.
Any other thoughts on what it could be? Just got the diagnostics book in the mail, the big black one 4-1/2 inches. Maybe it will shed some light???
Jeff