Wont stay running please help

hello.5.8 litre gas auto trans. my van stalled the other day and wouldnt restart. when i got it home it would start and run for about 30 sec. then would shut off like it ran out of fuel. replaced filter and front fuel pump and pressure regulator. also changed the ignition module. the van has 2 fuel tanks. if the rear pump goes bad can i still run on the front tank only. it does have a selector switch.please help

1991 ford e350 van. 5.8

Is the selector switch working properly?

its switching back and forth but the rear fuel pumg gauge isnt working it reads empty when i know its full. the front does though.

The fuel pump relay may be causing the trouble or the ECU is shutting down the pump for some reason. You could try replacing the fuse for the fuel pump with a current meter to make sure the pump is getting the proper currnt flow when this trouble happens.

This is wired from starter relay to dash fuel switch.

But once it’s running & the oil pressure switch is closed the pump is powered from the pump relay.

Could be a bad oil pressure switch, pump relay, or inertia switch.

A GOOD wiring diagram is worth it’s weight in gold at times like this.

OOPS, getting my Fords mixed up. An 86 is wired as I described above. Not sure if your 91 is the same.

If the problem is fuel related I’ll throw this possibility out there.
The fuel pump relay is activated by the ECM which receives a pulse from the ignition module. A ground is provided to activate this relay.
When the key is first turned to the RUN position a separate ground is provided internally by the ECM for a few seconds. This primes the system basically.

After a few seconds this electronic ground disappears and it requires an ign. module pulse to maintain this ground. If the ECM has an internal fault it’s possible the second ground may not be made. The engine will run off of the fuel in the lines caused by the prime and then it will sputter out due to the fuel pump relay not being activated.

Ford has several different methods of wiring this whole mess up and none of my diagrams covers a 5.8 van. It should, knock on wood, be very similar or exact to others.

Can you look at the diagnostic connectors where the codes are pulled and note if there is a tan/green wire in that bundle or an orange/blue one and let us know?
If you have a tan/green try running a jumper wire from that wire end to ground. The pump should activate and the van should run. If it keeps running then it’s back to verifying if you have an ECM fault or whatever.

If the problem is electrical (maybe no spark, etc.) then you should consider the electrical part of the ignition switch. Age and high current draw can toast the switches over time.
(One reason for this is that on most Fords the current draw of the cabin fan is run directly through the switch. The current draw is fairly high on a new motor and once the motor gets worn the current draw goes way up; even double. This means that a chronic dragging cabin fan motor can kill the ignition switch over time.)

Hope some of that mess helps you out anyway.

thanks every1 i will try all of these things. cross your fingers for me. thanks again.

hey ok4450. it does have an orange and blue wire, no green and tan though

I agree that you need to ground the pump relay as OK4450 mentioned.

Take a look at this link, it should help.


Is this the connector that you are looking at?

hello ranger. yes thats what im looking at. can i use the sharp end of a test light to the dia. plug and the alligator clip to the neg on the battery, or do i have to us other metal to groung? thhanks

Neg post of the battery will work.

thanks alot ranger ill give it a try.

well ranger thats not the problem, i can hear the fuel pump running when i ground it, it still dies after a few seconds. any other ideas?

Well, that rules out a problem with 90 percent of the pump circuit.

Heres how it works. When you turn the key one click to the “run” position the ECM grounds the pump relay and you should hear the pump run for 2 seconds.

When the engine is running ignition pulses tell the ECM to keep the pump relay grounded.

If this isnt happening there could be a problem with the ECM.

When you turn the key one click to the run position do you hear the fuel run pump for 2 seconds & do all the idiot lights come on including the check engine light?

yes all that is right, pumps comes on for prime then stops. when i grounded the the plug the pump was still running until i pulled the test light. this is driving me crazy, lol. if the rear pump goes bad does it disrupt the system? or can you just run on the front fuel pump? i appreciate you helping me ranger.

Since the pump does prime, the only possible problem that would keep the pump from running is a bad ECM or a problem in the ignition system.

Either of these problems should show up as a trouble code.

Best thing to do now is to hookup a scanner & pull the codes.

its dead in my driveway cant get a scanner, how can i test the ignition?

Hookup your timing light to any plug wire. Do you get a good strong flash when you crank it?