I just bought a '94 F150 with a front tank that doesn't work, and it fills from the rear tank. I've not changed a fuel pump from this year truck, but is the check valve built in with the pump housing itself? So by replacing the front pump that doesn't work, the syphoning problem would be fixed too, correct?

Also, I've priced fuel pumps online and found a range of $130 to $400 with different model years of compatability. How could there be such a huge range in price? I.E., is there a specific type (or brand) of pump to stay away from?

Thanks guys.

 

the check valve you're looking for is still available from Ford, and it's not that badly priced.

as far as the pump pricing itself, the $400. are modules, that include pump, strainer, and fuel tank sender as one unit.

 

I thought the check valve was part of a fancy fuel pump contraption. So are the check valves and fuel pumps separate and changeable by themselves? If so, where is this check valve?

 

OK, so I've gathered that the fuel pump, shuttle valve and check valve are all within the tank.

>>Can these all be replaced individually?
>>How does one know if the shuttle valve or check valve is bad?


Symptoms: No front pump whine and the front tank is filling while being run off the rear tank.

 

Yes they are.
NO
You can put a fuel pressure gauge on the fuel manifold and if the pressure drops fast it is the check valve. If it holds it is the shuttle valve.

 

Thanks subford. So the fuel pump for this year will include the check valve and shuttle valve then eh. My '88 with dual tanks just has a normal pump & pickup assembly inside the tank, which wasn't that expensive.

I guess I'm seeing conflicting info., or maybe there are differences by year that's providing the confusion. I'm not sure why I'd hear about some people replacing just the valve. The other thing is when I search for fuel pumps, I'm getting just a huge range of options so I'm not sure what to even purchase.


Anyone know what the price should be for the pump assembly that I need for this 94?
Thanks!

 

I found this on Edmunds, which makes the most sense so far. Now the question is how to I know that I'm ordering the correct fuel pump assembly or is it a FDM?


"One of your fuel pumps has a bad check valve, (or somebody sold you the wrong pumps). When gas is pumped to the engine, what isn't used is pumped back to the gas tanks. If your check valve has failed, the gas doesn't go back to the proper tank, or the front tank just pumps into the rear or vice versa, and could starve the engine too. The Hazard the tank could overflow and cause a fire. Ford had a recall for this problem, but I don't think '94 models were included.

The check valve system is built into the fuel pump. it's called a "shuttle valve," When the shuttle valve fails on one pump, it lets the other tank fill it up, when it's supposed to be checked. The shuttle valve is in the in tank fuel pump (FDM - fuel delivery module) for 90 to 96, according to my Haynes manual. Haynes says the damaged valve can't be repaired. You need to replace the whole fdm drop in unit it comes as one piece with everything.

When the fuel is cross flowing to the other fuel tank in your case to the front tank then the FDM shuttle valve is stuck open. Get a Haynes manual, it has step by step instructions. I did a search and found: "If you have a pump in each tank the problem is with the tank that is being filled while switched to the other one. If you are running on the rear tank and the front tank is being filled the problem is with the check valve in the front tank (stuck open). Replace the front pump unit. If the rear tank is being filled while running on the front tank, replace the rear pump unit." So it sounds like your rear check valve is the problem."

 

same item.


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Thank you subford for the diagrams!

 

....and thank you for the corrections within the excerpt I had found posted! I just noticed them actually.

 

I had the same problem (91 F-150) with the return valve in my tanks, feeding one tank from another. I was researching how to bypass one tank and just use the other, when a guy at an autoparts store told me there was a recall. I took it to a ford dealership and they returned it a couple days later fixed, no charge. I've never had a problem with it since.

 

i have 93 f150 change the pump only in rear tank now 10psi so the check valve is bad right thanks mikec

 

if you have a bad check valve will you have low fuel pressure
thanks mikc

 

My front fuel fills up front tank from the rear tank when i park with the front downhill. Both tanks work fine if I switch tanks. Truck run great like always on either tank. But I park with my front downhill a lot and I will go from a 1/2 rear tank and a 1/2 front tank to empty almost on rear tank and fill on front tank now. I read something about a check valve somewhere may need fixing?????? Where do I start first? 1991 F150 Ford, duel tanks, 5.0

 

Well mine does it running or not , ( Gravity ) into the front tank while parking downhill I guess. So would that mean the front tank is the problem for taking gas in or the rear tank for letting the gas leave the tank. ( Motor is off ). Once again I make the point this happens when i park over night ( motor off ) With my tank switch pointed towards front tank. Pamm