The truck is a `95 F-350 7.5L 4x4 Off-Road Pickup with dual factory gas tanks (high miles but a very nice truck.)

When I switch to the rear tank, the front tank eventually fills up with gas as I drive it. The gas pressurizes the tank if I drive it long enough to completely fill it. I have viewed all the information in a couple of Chilton type books and cannot pin-point the problem part. My parts guy cannot find a switch-over valve in the fuel line for switching between tanks so I presume that one or the other of the in-tank fuel pumps runs and the other has a one-way valve in it to keep gas pressure in the line and out of the tank. This one-way valve in the pump is the part I suspect.

However, I cannot tell from the diagrams in the books exactly how the gas from the pressure relief valve in the fuel loop gets back into the tank? Is it back through the fuel pump or does it have a separate path back into the tank? I don't want to go to the trouble of R&R'ing a fuel pump only to find I didn't replace enough parts (like a valve of some kind in the return fuel end of the loop.)

I have already acquired the tool needed to release the fuel fittings when I replaced the fuel filter earlier as well as a tall walker jack for lowering the tank. Any advice on popping the fuel tank out? Are the hoses long enough above the tank to see the fittings to disconnect them? Or, am I going to be doing it by touch?

I need to have my ducks lined up because I live in PoDunk Colorado and getting parts here is frequently a several-day proposition. I want to get all the parts I need before-hand and try keep this down to a one-day operation if possible.

Thanks,
Dan is Colorado

 

Probably best just to pull the box off the truck. There was a TSB out on these trucks and Ford Replaced both pumps free of charge. The two fuel pumps work together and should be replaced as a set, the fuel return valve(shuttle valve) in the pump isnt letting it back into the rear tank or the front tank return valve is stuck open. The fuel will travel to the tank with the least resistance. If you have the time, just replace the front pump, If you have more Money than time, replace both pumps and be done, With high mileage they are probably both on the way out.

 

Thanks, Rossman. I'm certainly interested in that TSB. Can you tell me where to get more info? It would save me $160/tank if I could get Ford to do it.

I did re-read the Chilton and reviewed the wiring diagram. I do believe all the valving is in the pump module. And, if I did pop the box, does unhooking all the wiring make it worth it or do they go through a gang connector?

Thanks,
Dan

 

A friend of mine has just experienced the exact same problem,, can't find the TSB though, Would like to find a hard copy to enforce 'our side 'when going to the dealer, vehicle has over 150k.

 

See corrected post below

 

There was a recall in 1993 regarding this issue. Ford's fix then was to install
extra check valves in the fuel supply lines. I have appended the text below. At the time, Ford extended its warranty relating to tank overflow to 12 years and 150000 miles.

There was a differnet recall in 1991. This was for the earlier design fuel selector valve. I appended that text also.

I don't know if there was yet another recall/TSB on thisissue, post 1993. My alldatadiy subscription doesn't cover your 1995 truck. You might try emphasizing the safety aspects of this problem to the local dealer, or to the Ford regional rep. Ford ought to be sensitive to the potential liabilities here.

Recall 93V125000: Fuel Pump Check Valve Malfunction

A MALFUNCTIONING CHECK VALVE WITHIN THE FUEL PUMP ASSEMBLY CAUSES A PORTION OF THE UNUSED FUEL FROM ONE TANK TO BE RETURNED TO THE SECOND TANK. WHEN THIS OCCURS, THE CAPACITY OF THE SECOND TANK CAN BE EXCEEDED, CAUSING FUEL SPILLAGE. SPILLED FUEL CAN RESULT IN A FIRE WHEN EXPOSED TO A SOURCE OF IGNITION. REPLACEMENT OF THE FUEL PRESSURE REGULATOR AND INSTALLATION OF REDUNDANT CHECK VALVES.

SYSTEM: FUEL; FUEL TANK ASSEMBLY.

VEHICLE DESCRIPTION: LIGHT TRUCKS AND CHASSIS CABS WITH GASOLINE ENGINES AND DUAL FUEL TANKS.

NOTE: IF YOUR VEHICLE IS PRESENTED TO AN AUTHORIZED DEALER ON AN AGREED SERVICE DATE AND THE REMEDY IS NOT CORRECTED WITHIN A REASONABLE TIME WITHOUT CHARGE OR THE REMEDY DOES NOT CORRECT THE SAFETY-RELATED DEFECT OR NON-COMPLIANCE, PLEASE CONTACT FORD'S CUSTOMER ASSISTANCE CENTER, 300 RENAISSANCE CENTER, P.O. BOX 43360, DETROIT, MI 48243. ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S AUTO SAFETY HOTLINE AT 1-800-424-9393.

Recall 91V146000: Fuel Tank Selector Malfunction

THE DUAL FUEL TANK SELECTOR VALVE MAY MALFUNCTION AND CAUSE AN OVERFILL CONDITION IN ONE OF THE FUEL TANKS, RESULTING IN AN OVERFLOW OF FUEL PAST THE FILLER CAP.

THE OVERFLOW OF FUEL PAST THE FILLER CAP CAUSES A FUEL LEAKAGE, WHICH CAN RESULT IN A FIRE WHEN EXPOSED TO A SOURCE OF IGNITION.

REPLACE THE DUAL FUEL TANK SELECTOR VALVE.

SYSTEM: FUEL TANK, AUXILIARY.

VANS AND LIGHT TRUCKS WITH DUAL FUEL TANKS PRODUCED IN THE FOLLOWING PERIODS: F150, F250, AND F350 LIGHT TRUCKS BUILT BETWEEN FEBRUARY 28, 1989 AND JULY, 1989; ECONOLINE BUILT BETWEEN FEBRUARY 28, 1989 AND FEBRUARY 11, 1991.

NOTE: FORD HAS AGREED TO RECALL THESE VEHICLES BUT PARTS ARE NOT YET AVAILABLE.PARTS WILL BE AVAILABLE IN DECEMBER 1991. YOU WILL RECEIVE A LETTER FROM FORD ADVISING YOU WHEN TO SCHEDULE AN APPOINTMENT WITH YOUR DEALER TO HAVE THE RECALL WORK PERFORMED. IN THE MEAN TIME, YOU CAN TAKE THE FOLLOWING PRECAUTIONS:FILL EACH TANK TO ONLY 1/3 FULL. IF YOUR VEHICLE LEAKS FUEL OR IF YOU SMELL FUEL, STOP USING THE VEHICLE AND CALL FORD AT (313) 446-4654 AND ADVISE THEM OF YOUR PROBLEM. REFER TO FORD SAFETY RECALL NUMBER 91S39. AN OPERATOR WILL TAKE YOUR NAME AND TELEPHONE NUMBER. A FORD REPRESENTATIVE WILL CALL YOU BACK.

 

I just got my 90 f-150 and it appears to have the same problem. Im wondering, since it is a safety issue, are they still fixing it free?

 

THE recall is almost 20 years old. I am not 100% but willing to say ...... I would not hold my breath on the recall still open. The 1990's had a different setup. Your 1990 should still have the sector valve / bowl set up. ( black bowl looking unit on the frame under drivers seat ) This set up uses fuel pressure to switch the lines between the tanks. I think some of the 1991's had the newer setup. I know for sure 1992 they changed. Got rid of the 3rd pump on the frame, put high pressure pump's in each tank. The 1997-1991ish used a low pressure high volume pump in the tanks. They feed a small bowl on the frame, then a 3rd pump ( on the frame next to the bowl / switching unit ) was a high pressure low volume that feed the fuel rail for the injectors.

IF your setup still has this setup 95% sure its your problem. You might be able to repair it. Last I knew there getting pretty hard to find new ones. I am not sure if ford is still making them.

 

Yea, I did some research, some say 10 years, some say 15. Either way, Im way beyond that. Getting old sucks lol.
thanks for your post. Im gonna get the truck in my driveway next week and start systematically going thru it after I check what you said and I have one other idea. But first of all, I want to see if it stops doing it when its not on a hill.

and you are right, finding those is getting hard, but it does look like something you can repair. Shame on Ford for not making them anymore. So many of their old trucks still on the road.

Man, they can put a man on the moon, but they cant seem to get this thing right lol. I mean, so many changes in such a short time, what the heck. Dont they have engineers with multiple degrees working on it, or do they have monkeys. I could understand if it was a GM, :

 

Yes,
They had, and still have monkeys
I still happen to have one of the selector valve recall parts kits

 

You do realize that the post before yours was May 2021?