ok after reading the numerouse post on this problem could someone tell me(not a mechanic)what part Ineed to get to regulate this problem.As some many people had opinions on the fix straight up please.Thanks Confused

Part name

Part # if possible but it would probably be differant for me in canada

 

Check valve in the fuel pump/sender assembly.

don't know the part #s, but thats whats doing it.

 

Ok so for my truckk 1988 dual tanks your saying its the check valve correct?
Should I change the pump also $72 for pump?

Do they sell the check valve or do I have to buy the hole sender unit? My gas gauge works fine so the sender unit is good

 

is this what i need? Selector valve assy for my rear tank?

 

There is a check valve inside this entire assembly that can go bad, BUT, Ford does not sell that part alone.
You have to replace the entire unit as one.
I called my local Ford dealer just now and they normally have at least 1 in stock at a cost of 136.00 plus tax.

 

The check valves were only used on 90-up trucks (maybe 91). The '88 in question here uses a fuel pressure operated selector valve on the left frame rail, just aft of the high pressure in-line fuel pump.

If you can verify that each of the in-tank pumps are working properly (test pressure and flow rate), the selector valve has stuck in between the two positions and is allowing fuel to go from one tank to the other. If it's something stuck in there, you may be able to clean it and get it working again, but it might be quicker and easier to buy a new selector valve. Again, test the in-tank fuel pumps before replacing anything.

 

if a pump is acting up the pump could cause the same problem?

 

The pump CAN cause similar problems.

4 years ago the front pump on my 96 was doing some real funky things.
Hard starts, Hesitation, Running rough, Overheating, After much reading and bothering my local Ford dealer in Pennsylvania, I finally found out what was causing the problems. BUT, The problem I had, was the indications did NOT point to a pump, It pointed to a problem further into the fuel system itself.
It was til after the front pump totally failed that it all made sense.

During that time I used my rear tank. I would fill my rear tank and go thru 19 gals of fuel in 3 days. When checking tanks and seeing a puddle of gas under my truck one morning did I find that the fuel was being diverted to the front tank and overfilling it. I blocked off the lines and have not had a problem since.

I recently bought a fuel pump for my front tank on ebay for 35 bucks and have not yet installed it. To be honest, I am hesitant to do so since I KNOW for a fact that my fuel selector valve assembly on my frame rail is also malfunctioning. I use my 96 for snow powing for another reason and cannot afford to be down for several days for mechanical repairs that can wait til spring. Once I can get the front tank dropped again and replace the pump, I will also replace the fuel selector assembly and see if it corrects all the problems.

 

A failing fuel pump could cause cross-flow issues on the 88 with the external selector valve. Since it is operated by fuel pressure from the in-tank lift pumps, if one lift pump is not working, there is a possibility that the valve could get stuck on one tank or possibly between tanks and cause a cross-flow problem. This is why you should check the in-tank lift pumps before spending any money on the selector valve.

The 96 referred to in the previous post should not have a selector valve on the frame rail. All of the switching is done inside the tanks in the fuel delivery module. To truly fix the cross-flow problem on the trucks with high pressure in-tank pumps requires a new fuel delivery module/pump assembly.