I have a 1996 F250 351. The truck runs fine now after replacing the FPR but when I run off the rear tank, the front tank slowly fills. One tank is fine for me. I would prefer to run off the rear tank. Can I simply block (perhaps install a shutoff valve) inline with the front tank return line?

Would this create a catastrophe if I accidentally hit the tank switch?

Should I unplug the front tank pump as well?

Someone has surely eliminated a tank before? What is the easiest fix without replacing the faulty pump

Thanks,
Mike

 

I removed my rear tank last year. No problems so far.

 

I slung a U-Joint when doing 80mph down the high-way. Broke the drive-shaft, Exhaust, and tore a hole in my front fuel tank....I ended up removing the front fuel tank. I unplugging the harness and tied it up...The fuel lines I dissconected from the fuel pump and bent them to were no leaks are present....Ghetto I know but at the time I was broke for having to get a new drive-shaft, catalytic converter and a muffler. 12 years ago and its still like that today held by the same tie strap to this day.....

 

The front tank is the larger of the two, so it would make more sense (to me) to run off that one. Leave the switch in the "front" position and put a piece of electrical tape over it so it won't get bumped. Otherwise replace the rear pump module and have two functioning tanks. When I'm going to be towing, hauling, or working the truck all day its nice to be able to fill both tanks and just run without needing to stop.

 

check for safety recalls. I took my 88 dual tank in, when the fuel was flowing from front tank to and out of the rear tank, to the dealer. They fixed it at no cost to me, about 4 years ago. Works great now.

 

Thanks for the ideas guys. BLKF250HD, because when I run off the rear tank the front tank fills up......isn't it my front pump that needs replaced? I am trying to learn all a bout this Ford tank issue.

 

If it is like mine, there are 3 pumps. One in each tank and on near the drivers feet on the frame. The control valve switches off of the pressure from the tank pump. The control valve is the problem and is not switching correctly.

 

In 1996, there was no control valve, the lines are shared, but only the running pump is supposed to allow fuel back into that tank.

I believe this means that, if one tank works "right" and one transfers fuel, the problem is with the pump in the tank that works correctly, it is not shutting the return valve while unpowered

 

No it's not like yours, pickups built after 1989 only had in-tank high pressure pumps.
Removing a tank and plugging the lines(you have to plug both) works fine and is easy enough to do. Just get a couple engine studs and cut the threads of 1 end so that the smooth shank fits inside the fuel line. There is an O-ring in there that will seal against the stud. Next shape the head of the stud so that it can be retained with the factory retainer clips, wrap the electrical connection in plastic and strap everything up out of the way and you're done. Note that you need 2 different size studs for this, the return line is a little smaller. Here is one of the plugs I made for my truck..

 

I cut my t connector out and replaced it with a barb. Done deal.

 

When I run the front pump.......everything is fine.

When I run the rear pump the truck runs fine but slowly fills my front tank.

My front tank pump needs replaced correct??? The check ball is not functioning properly within the front tank pump .....correct??

My truck is a regular cab long bed 96 F250 351. Are the pumps in each tank identical?

Thanks guys,
Mike

 

Yes the front tank pump unit is causing the issue with the tank filling off the rear(when rear is used).

Not sure if both pump unit are the same between the tanks. One may be longer than the other.

 

Ford acknowledged tank-to-tank bypass issues and recalled affected years in order to install inline check valves. Your "easiest" solution would be to obtain said check valves or replace FDM-
Either way tank must be removed.
IMHO removing tank is not terribly difficult but not something I want to do often so I would replace FDM and be done with it.

FDM (Fuel Delivery Module) is basically pump w/screen, & check valve housed in a reservoir and were designed to replace earlier frame mounted fuel reservoir/tank switch valve.

I do not know which year fuel lines changed but sometime after 1991 fuel lines where change from poly lines to a combo of steel lines and armored flex lines.
Poly lines can easily be spliced and repaired/replaced.
Later steel/armored flex lines are a bit more challenging to modify.

I bypassed front tank on my 1990 F-250 for a cpl years by simply using barb fittings from auto parts store in pressure and return lines.
Recently I replaced front tank and reconnected everything (great for my purposes to have both tanks again) simply by reversing what I did before (simple because I saved factory barb Y fittings).
Later armored flex/steel lines make tank deletion difficult at best and possibly hazardous.

 

I can't justify spending the money to get both tanks working again on my truck.
The filler necks alone are $200 each and the pumps are about the same. I don't mind using one tank and filling more often. It saves some weight and reduces the amount of frame rust. My frame is noticeably thinner where my rear tank was because it trapped moisture between the tank and frame. No more.
I can always make my tank bigger or make a new one. The dual tanks tend to be trouble when you need them the most. The only way they come in handy is if one pump burns out. I have thought about going back to carb just to get away from the electronics, but can't seem to commit to it.

 

FDMs exterior reservoir shape is necessarily different because of the way they hang in tank-
*rear hangs at approx 45 degree angle with strainer sock flat on tank bottom
*front hangs vertical also with sock flat on tank bottom
FDMs will not interchange and function properly.
Sending unit arms are tank specific also.