I have an F250, dual tank, 7 liter gas engine, 1993, which now only operates off the rear tank. Seems that the pump in the rear tank pumps gas to the engine but gas also goes to the front tank until it fills up and begins to overflow. The truck can be driven but, with gas leaking out of the front tank while the truck is being driven, a fire danger is ever present. I was told by a mechanic that the pump in the front tank had a defective check valve which permits the pressurized gas from the back tank to flow into the front tank. I purchased a new pump for the front tank but think I am only guessing at what causes the front tank to leak gas.

I first noticed this problem a year ago after all gas was removed from both tanks by thieves and wondered if that could have damaged something that would have resulted in the front tank overflowing when driving.

If the front tank needs a new pump with a functioning check valve, is it best to remove the truck bed and attach the new pump from the top instead of dropping the tank from under the truck? Might my problem be cured by replacing a "selector" valve n a side frame rail?

Thanks for any response.

Nick

 

Your truck doesn't have a selector valve so you'll have to replace the fuel sending unit in the front tank. It's far easier to drop the tank its just 2 bolts on the straps after you get the skid plate off. Removing the bed is almost always a nightmare because the bolts sieze and the bolts have to be ground/cut off.

 

I got the same problem, but, My front pump is out (truck won't run on front tank at all) and the rear pump pushes fuel out the front tank. My question is should I replace both pumps and shuttle valves to be sure I'm getting the right shuttle valve replaced? I'm currently siphoning gas from front tank and putting it in rear tank every two days. I not a happy Ford Truck Owner at the moment. It looks to be about $300 for the pair. bjr23

 

You just have to do the front tank.
You would only replace the rear one if the rear one was filling or it did not pump.

 

I have a '96 F-150 w/ 351 4x4. I think this thread answers my question, but want to make sure:

Truck starts, but runs rough on front tank then dies. Starts fine on back tank. Can start on back tank, switch to front tank - sometimes rough, sometimes fine, but get pinging and varying shudder (mild).

Back tank pushes fuel to front tank, but not front to back.

Still a little confused on what my problem is.

Question is: Does mine need a new front pump, switching valve, sensor, etc.

Thanks for all the help.

 

You need a new front FDM, your truck has no switching valve that ended in 1989, and there are no sensors inside the tank except the fuel level sensor.

 

Sounds like a **** poor mechanic. You can tell him I said that.
Find another mechanic. The one you have is stupid or a crook.....or both.

 

92 250,truck duel tanks, Mine rear fills the front. Ive been reading everythread on this for a while.I know about recall 00S57, and 93S68, Called dealer & Ford themselfs they are no help tuff , I,m past the 12Yr 15000. mark Plus they can,t find there own part kit, to repair. say,s gone after 10 yr,s I have the FORD technical service bulletin in my hand 14 pages worth with part no# and the how to do for the tec, for the repair. Still no help there, The Kit for my truck, was F4PZ-9155-D There cost 25.oo When they punch in those no# absolete, It was kit with Fuel pressure Regulator and the two check valves, one for each tank. A crosscheck no# got us to a 1L329J274-AA is the in line check valve,And had only one,99.00 later is in my hand. Is this going to do it? What happinened to the kit F4PZ??Have to lower tank down but not out to get to it . Would i be better to just change the Pumps, They do work can hear them when you switch back and forth. so Replace Fuel pump regulator, haveing hard time even finding one as there is no part no# for it Or the Check vale,s that some also called the regulator or the pump,s or just drop the back tank pugg off the lines and be done with Thank for any help Jeff

 

SusitnaAK,
There is nothing wrong with your rear tanks FDM (pump).
You need to replace the front FDM (pump) and you will be good to go.
The filling tank always has the bad valve in its FDM.
The Fuel Pressure Regulator was bad for the 1993 year truck as they had a bad run on them and it let the fuel pressure go too high.
The check valve was going bad because the supply line pressure was way to high so this took out the valve in the non running tank.

From reading a lot of posts on this site it now seems shortly after a check valve goes bad the pump also stops working. This leads me to believe that something is coming apart in the FDM maybe from the pump and the debris is getting under the check valves seat. So now this tank starts to fill while on the other tank and its pump on the filling tank soon quits.

So to answer your question no I do not think putting on outside check valves or plugging the rear tank is the way to go.

 

OH i was hoping you woudn,t say that What was i thought to , Changing both pump,s seems like the way to go . BUt it cold up here now trying to wait for summer looking for easy fix to get me though the winter. The pumps are only 50.00 more not counting the work involed Thanks for the reply Jeff

 

I have the exact problem this thread explains. The gas from my back tank pushes out of my front tank all over the ground. I am trying to sell this truck and need the most cost effective way to fix or what part do I need. From the dealer or wrecking yard? I think it is the fuel selector valve that is bad and I believe it is not electrical but mechanical or vacume. Correct me if I am wrong. Thanks in advance for any help.

 

You are right.
It is the fuel selector valve and it is mechanical and NOT electrical or vacuum.

 

I just called Ford bout this , my 1993 is doing the same thing ... the kit is 135 bucks and its a over night shipment.
i just ordered one , gl to you all!
jayson

 

We're talking about old tanks, with the rear area full of 15 to 20 years of debris. I found it easier, on my 89, to pull the bed. The only bolt with an "issue" is the on the left side front, right next to the tank and the plastic fuel lines. The hot wrench would not work here, but grinding the head off with a side grinder was easy. The bed lifted off easily with 4 guys (cost me a lot of beer) and then I was able to pressure wash the whole area, and the tank units were easy to remove without the contamination of dirt etc. It was putsy to do that way, but I've done them both ways over the years and would recommend taking the time, using lots of patience, and go for it. If you've got real rust bucket may not........

 

Same problem here. Showed up yesterday on my 88 F-350, 7.5L. Switched to rear tank, and smelled fuel. Front tank was overflowing under truck. Removed fuel tank caps and confirmed by switching tanks multiple times. When rear tank selected, front tank overflows.

Would this also be a fuel selector valve problem as manlikesford's 89 as mine is an 88??

Also, is the photo in post #9 the part??