I have been tried to search on this but didn't find anything that was an exact fit.

I have a 93 F150 with Dual tanks. When running from the front tank I only get about 150 miles out of the tank. The last fill-up I did the following:

Topped off both tanks.
Ran the rear tank until it was down to 3/4 of a tank.
Switched to the front tank.
Ran it about 1/2 way down.
Switched to the rear tank.
The rear tank is now between 3/4 and full.

I think that there is a control valve between the tanks that is the culprit, but wanted second opions.

Is this something that I can clean and service or do I need to replace it.

Thanks,

Paul

 

a guy i know said it was somethign to do witht he check valves. I had the exact samething only in reverse. the back kept pumping gas into the front, so i thought I was getting really good gas mileage, but when i switched tanks. I ran out of gas.

 

The in tank fuel pump has a check valve built into it. You will have to pull the tank and replace the pump. I had a similar problem with my truck but ended up pumping a whole tank of gas from the front out the fill for the rear as i was going down the highway.

 

I have the same prob with my '90...i think thats why im getting horrible gas mileage, my back tank doesnt work b/c the pump went out, and its pumping gas into that tank from the front tank, i opened the cap from the rear tank one day and gas spewed out, needless to say i draned it all out and it hasnt happend since but im thinking about fixing the problem....but if the fuel pump doesnt work shoudlnt the valve not work either?????

 

It sounds like your having crossover issues. There is a recall on this through Ford...I would contact your local dealer and check to see if your truck still qualifies.

 

It sounds like you have a faulty check valve in the rear tank fuel management unit, or FMU. When a fuel tank is selected with the dash switch, the fuel pressure from the operating pump opens a spring loaded shuttle valve to allow retun fuel into that tank only - if you didn't know, the fuel pumps supply much more fuel than the engine uses and the fuel pressure regulator returns excess to the tank. What's happening in your rear tank is that the return shuttle valve is sticking open. The return fuel travels to both tanks while the truck is running. There is no net filling on the front tank because it is the selected supply tank...but the rear is filled up. If you don't manage this situation properly - ie, fill both tanks and select the forward tank - then you can overfill the rear tank and cause fuel to leak from the filler neck. Some of the earlier trucks were subject to a recall - if your truck is not subject to the recall, new FMU's are available at generic auto parts stores as well as from Ford. I think my generic branded replacement from Autozone was actually a rebranded Ford part, as it looked identical, and the part numbers and logos were ground off....intersting. Replacing the FMU is the same procedure as replacing an in tank fuel pump - it's just a fuel pump in a cannister with some extra plumbing.

 

Oh...I may have failed to answer the original question - the FMU must be replaced as a unit. The shuttle valve is an integral part.

 

There is a recall, it expired a looong time ago though.

 

The recall on 93's is for 12 years or 150,000 miles which ever comes 1st. Just had check valves put in on mine at 101,000 a couple of months ago.