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have an e250 with dual gas tanks. when first starts up it runs for a couple of min and then shuts off. i hooked a fuel gauge up to it and the pressure starts out at 33psi and goes to about 5psi and shuts off. it doesnt matter what tank its on it does the same. i replaced the relay and still the same thing. any suggestions.

Seems like to me the early model efi's that had dual tanks and no switching valve relied on one way valves to keep fuel from returning to the wrong tank. The valves are in the tank.

I thought the switching valve was mounted on the left frame rail. I used to work on alot of them and the valve was a constant source of frustration. It has been quite awhile since I have seen one of these era pk tks and I may be wrong.

Ford used 2 types of transfer valves in 1989. One is electric and uses a small motor to switch from tank to tank and the other is pressure activated. Both were troublesome back in the day. Look for wires to the module. The pressure activated units are round and have a filter in the bottom of them. You'll need to identify which system you have first.

i have the one that has the filter looking one.

OK. Both designs had flaws. If I remember right, you can check that filter and see if it's plugged. Getting a replacement if it is would be another story. I remember that when they failed, the valve would not fully move over. I used to check them by removing the assembly and checking the throughput. I'd highly suspect the changeover assembly if the problem exists on both tanks.

Some of these systems use a secondary pump on the frame rail along with the pump in the tank, totaling 3 pumps for a dual tank system. Make sure you don't have one of those.

Not all of those that appeared to have filters had filters. back in my Ford daze we'd find some that had no filter right from Ford.

Yea, I also run into some that had filters while most did not. Our local ford dealer here still has them available.

it does have that other fuel pump along the rail witch i did replace. but still have the same problem. can that canister looking filter be the cause

Are you still getting 12volts at the pumps when it loses fuel pressure? Sounds like the pumps are shutting off to me.

yes

I remember a few of those whose rail mounted pump worked but the tank mounted pump did not. The truck would start and run a bit, then as you drove it would die out.

If pump has power and ground and is not not pumping then its the pump?

yeah but whats the chances of being 2 pumps

i'm pretty sure the main pump is on the frame. it may be sucking air from a bad change over valve. we haven't decided if the pump is shutting down because of no spark. i really don't suggest this on a regular basis but spray carb cleaner into the air intake and see if it will maintain. if not suspect eek relay or rotted wire. the grounds had a habit of rotting at the relays. the relay plugs were famous for rotting.

civicsi1279 wrote:yeah but whats the chances of being 2 pumps

not likely, but possible. I'd lean more towards the changeover valve.

i checked this morning to be sure and it say's "the electric fuel pump system consists of two fuel pumps. a low pressure pump on the fuel tank and a high pressure pump mounted on the frame rail. an in-line reservoir is located at the high pressure inlet. this design provides for satisfactory fuel pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fill levels." he switch valve is the reservoir. i'm trying to recall when the switch was used as a filter housing. i know there was certain ones that did while others didn't. best way to find out is see if there is an in line filter. if it's not visibly present it's in the switch valve. if the filter is in the valve and plugged you will get a start and fade but you'll hear the pump straining. as i stated above, i had so many issues with the relays failing i stocked the eek and pump relays along with the plugs. if in fact you find it's the plugs that are rotted even though they look alike and the relays will plug into either one they are wired different for amp loads. keep us posted. i like talking about older vehicles it exercises the brain.

pulled the rear tank down and found rust and dirty gas inside. fuel pump was all rusted and corroded. replaced the tank and fuel pump and fixed the problem. they didnt want to do the second tank but assume the same problem with that one to.

civicsi1279 wrote:pulled the rear tank down and found rust and dirty gas inside. fuel pump was all rusted and corroded. replaced the tank and fuel pump and fixed the problem. they didnt want to do the second tank but assume the same problem with that one to.

rereading the original post i'm wondering if it's only feeding off the rear tank. it doesn't make sense that replacing the rear tank would solve the problem. at the beginning you stated that it didn't matter what tank it was on the symptoms were the same. i'm wondering if the switch is changing over to the tank sender but the valve is stuck on the rear tank. just a thought, i've seen it before............................thanks for keeping us posted