from bat out of hell to nothing 94

[garagedog369]

I have a 94 sport. I blew the heads out of it last fall. installed new heads.it hast ran decent since. ran the codes, always came up with the egr or one of it's controls replaced all 3. still ran I ****. there was really no fuel pressure at times ,so replaced the fuel regulator., then the fuel pump and filter. along with the mass the mas flow senor.
it idles very nice at times, then lopes along, bearly running at times. running it. is something else.it either has all the power you want or nothing. it gives you power down the road for about 2 miles then , no power for about 3 miles. then cycle will start all over again. can't find any leeks of any kind.no fuel leeks, haven't lost any fluids, that I can tell.
could the fuel injectors. be the problem. need this running by the time snow flies in south Dakota. hope someone can help.
one more thought. I do not have a fuel pressure gauge. but even now. I can turn the key on listen for the fuel pump, when it shuts off. I push the valve , where you would put a fuel pressure gauge. and their is no pressure in the fuel rail. there is no fuel leeking around around the fuel in jectors.

 

[Centaurious]

looking at everything you have done can only think of two things to try.

1) Read the codes and see if they give you a clue or two.

2) bypass the power to the fuel pump. Find somewhere you can interrupt the power and ground to the fuel pump and splice in a headlight bulb or something to provide a load on the computer side. On the tank side provide your own power and ground so you know the pump is being supplied with power. Then test drive.

I suspect that there may be a problem with your ECM- Engine Control Module. The computer supplies the power and ground for the fuel pump, that is why it cycles briefly when you turn the key on. I suspect that you are loosing and re-gaining power as you drive because the fuel pump is powering weak and then back to full voltage but this needs to be tested.

 

[garagedog369]

well I just have 2 ECM's in my garage. pluss one in a 94 that I wreaked over the winter. will try that. later this afternoon.
thanks.i will make sure the #s match.

 

[MrShorty]

one more thought. I do not have a fuel pressure gauge. but even now. I can turn the key on listen for the fuel pump, when it shuts off. I push the valve , where you would put a fuel pressure gauge. and their is no pressure in the fuel rail. there is no fuel leeking around around the fuel in jectors.

Sounds to me like it is time to beg, borrow, buy, steel a fuel pressure gauge. It sounds like something is wrong in the fuel system, and it is time to systematically diagnose it.

I will note that this "off/on" power thing sounds similar to symptoms I had when I got a bad "new" fuel pump and installed it. When the pump worked correctly (generated adequate fuel pressure/flow), then I had all the power one could expect from the 4.0. When the pump did not work correctly (fuel pressure dropped below ~20 psi), then it stumbled, hesitated, and stalled.

I can't say whether or not you got a bad fuel pump, or if there is something else wrong with the system, but I would be focusing my diagnostic efforts on the fuel system at this point.

 

[Rhett]

When you get the gauge, get one with a long enough tube that you can tape it to your windshield while it is hooked to the fuel rail port. You can then monitor the pressure as you drive -- when it stumbles, verify that the pressure hasn't dropped.

 

[garagedog369]

don't think it's the fuel pump, only because it had the same problem before I installed a new one. tried two other E.C.M.s. no change. but where is the ground on the fuel pump hooked to the frame or grounded. looked but didn't see it. yes a fuel pressure gauge is on the way will be here before the weekend. I've had ground problems before, not on this one, but in the past this is my 5 th explorer.

 

[MrShorty]

If I remember right, the fuel pump grounded to the body under the hood behind the coolant overflow/windshield washer fluid reservoir.

 

[Rhett]

If I remember right, the fuel pump grounded to the body under the hood behind the coolant overflow/windshield washer fluid reservoir.

Was this a ground wire that was included in the wiring harness for the fuel pump/sender? It must have been. Then run up from the harness to the body in the location you indicate.

I sure didn't see any external ground strap on my truck. I'll have to follow it down, and see if it enters that harness -- surely it does.

 

[MrShorty]

That sounds right. The pump ground came up through another connector with some other wires that also went towards the back. I also remember that, when I had the ground disconnected cleaning it or something, that it did some funky things with the wipers, though I don't remember details.