91 Exp just died.. turns over, plenty of power, put gas in, doesn't start | Ford Explorer Forums - Serious Explorations

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91 Exp just died.. turns over, plenty of power, put gas in, doesn't start


Active Member
July 21, 2004
Reaction score
City, State
grafton, Ma
Year, Model & Trim Level
91 XLT
E.C.C (ECC) relay keeps popping.. i must have a short. HELP!

1991 Explorer XL 4x4 V6

So my girl was driving my truck and she said it just stopped running. I went to pick her up (and eventually tow her home with my chains) but when i evaluated the situation here's what i found.

The engine turned over like a champ... plenty of power, but never lit up
All fuses looked fine.
I checked under the truck and followed fuel lines, there was no leaking....
I put gas in thinking maybe it was low (my gas guage is broken), and still no go even afer i let it sit for a while in case of flooding.

I'm going to tackle it tonight after work, what i'm planning on doing is taking a spark plug out and seeing if there's spark by holding it near a ground.

My only other question is, since is fuel injected, how might i find out if fuel is getting to the engine. Much like you would take an air filter off on a carborated engine and look for squirt squirt... how would i do this on the 91 V6???

Also, if i'm not getting spark.. what could have failed out of the blue like that to make that happen. Obviously not all my plugs went out because they were working great before. I'm hesitant in thinking it's fuel because there was no sputtering prior to it dying.

It's gotta be electrical, either an ignition module or the fuel pump just plain died.

let me know what you think

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it might be the fuel pump, sounds like it.

i cant think of a way that you can pour gas in fuel injected motor like you can with a carburator.

can you hear the fuel pump prime (kind of a whining) when you turn the car on (not turn the motor over)?

I know the whine you're talking about... i'll definitely give that a listen tonight..

My goal on the fuel thing was to maybe unhook a fuel line that goes to the fuel injectors.. then turn the motor over and see if fuel is spurting out of it. Then i'd know if the fuel pump is operating or not..

There's gotta be some stupid ignition module that controls whether or not the spark plugs get power or not. I'll find out tonight if there's spark..

In these situations.. the rule of thumb is that it's either spark, or fuel.... there's not much else it can be.

What you can do is push in the shrader valve on the fuel rail, looks like a valve for a tire, just press it with a screwdriver and see if it sprays. (Warning: Make sure you have some sort of eye protection in case it sprays into your eyes.)

SWEET!!! thanks man.. just the thing i was looking for. now, where's the fuel rail? i didn't see one when i was trying to disect it this morning at 7am

Definetly check to make sure the fuel pump it coming on for approx. 3 seconds when the key is turned to the position just before the engine cranks. If you don't hear the fuel pump run, I would check the fuel pump relay first. That relay went out on my '94 and I was able to tap on the top of it and it activated, allowing the pump to charge the fuel line and start. There are also like relays in the bank that you could swap positions with to test it out.

Is this relay in the fuse panel? one of those?

The relay is in the power distribution (black box) under the hood.

Yes, on the '94, it was under the hood on the passengers side. It was labeled on the legend that is under the fuse box cover.

interesting... i'll take a look tonight and if i cant find it.. i'll hit the engine with a sledgehammer.... umm.. i mean.. i'll get out my manual.

Ok... i'm home, and it took me 5 minutes to figure out the problem thanks to you guys.

So i turned the key, no whine.
so i said, ok.. fuel pump is either toast, or that fuel relay is gone. So i open the hood and start looking at the fuses. The fuel relay is fine. hmmmm

turns out there is a fuse that's busted... the E.C.C. Relay... can anyone tell me what this is??
So i pull out the "power door locks" fuse and put that in the ECC Relay slot.. trucks starts... but then dies again in like 1 second. I go and pull the fuse out again.. it's busted..

So i put a 40 amp in there... turn car over.. it starts, dies, and the fuse is busted.

Something is blowing away any fuse in that port.

NOW,... let's see how smart you guys really are (j.k.) ...

what do you think is blowing my fuses?

A short in the ECC circuit. What else is in that circuit?

40 amp seems high to still blow a Engine Control circuit. Something must be grounded.

Yea.. something's gotta be grounded.. but what.. the fuel pump itself?? what the heck else is on that circuit that could ground it???? anyone know what the ECC relay is and maybe have a circuit diagram for it?

What is on the EEC circuit? EEC=Electronic Engine Control. Basically, the engine computer, various sensrs, solenoids, and controls (including the fuel pump relay). You can find a decent wiring diagram in the vehicle repair guides at www.autozone.com (equivalent to a Chilton's manual). That will get you started.

Seems to be several recent posts on this lately, wierd?
turns out there is a fuse that's busted... the E.C.C. Relay... can anyone tell me what this is??
So i pull out the "power door locks" fuse and put that in the ECC Relay slot..
Anyway, trying to make sense of it all, how exactly did you check the fuel relay, before you changed the ECC fuse? Just to make sure, a relay is a little square box, and a fuse is clear (colored a according to amps) with 2 prongs. A FUSE should NOT fit in a RELAY slot.

Also, I believe on a first gen the relays are actually below the fuses in the Power Distributin Panel under the hood. You will need to the fuse panel to get to the relays.

Ok with that out of the way, the fuel pump is to operate intermitantly to maintain proper fuel pressure, the fuel relay should kick on and off to regulate pressure. Is it possible the fuel relay is stuck on causing the fuel pump to run constantly even after the fuel line is pressurized, drawing too much current and popping the fuse.

You may have a bad relay that caused the fuse to blow. Try swapping both relays and fuses.

Well.. The ECC relay (and it says ECC relay under the fuse box lid) is clear and does look very much like a large fuse. I noticed it was "popped" because the metal inside was severed.

I did some research on my own and found that ECC=Engine Control Computer
see http://www.kemparts.com/scripts/180.asp for my reference.

Then i also found this thread. Apparently this guy brought it to his dealer and his dealer said it was a hard short.. and said he could find it pretty inexpensively...


So i guess now i've gotta find a circuit diagram for the ECC and see if i can find some points to see if there's a short. I take it what I do is find a point in the line to test, put an ohm-meter on the line and touch the other end to ground. If it's 0 ohms.. there's a short.... correct?

oh man, i'm not looking forward to this crap.

It might be as simple as some wore off insulation on a wire. The hard part is finding where?

Wiring diagram for a 91 4.0 ECC here

I took my ohm-meter and ohmed out the two sides of that fuse point with the key turned on. One side was 0 ohms with + on the battery. The other side was 0 ohms with - on the battery. Thus, i'm getting however many amps the battery holds through that 30 amp fuse, thus the blowing of it.

Now, I've looked at some wiring diagrams of the engine and it seems the other side of this fuse goes to the EEC Power Relay. My question is, do you all think that somewhere there's a wire grounding out on the chassis, or do you think my EEC power relay is bad and should just be replaced? can it be replaced? might that be the issue?

thanks for your help...

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I think lonestar is right.... ????... you need to help us establish whether you are dealing with the ECC relay or the ECC relay fuse. They aren't the same... at least according to the schematic posted. In the referenced google document, that poster was referring to the ECC relay fuse.... not the relay its self. The fuse will only have two contacts while the relay has at least four. What you need to do is pull the fuse (fuse #8 in the fuse box) and measure it (although I believe your eyes if you are looking at the right thing when you say the metal is gone). Of course it needs to be a short (out of the fuse holder)... if it is still good otherwise open (high resistance). Next you need to pull the ECC relay or disconnect the hardness from it (not sure which) and measure the four connections. Two should have a low resistance (red lt grn to blk-wht)... it could actually look shorted as these are windings to operate the relay... could be half ohm so if your ohm meter is not calibrated, you might think it is a short... check it very carefully to get a good reading. Next the other two contacts should be an open (high resistance) because they are normally open when the relay is not operated. You need to do the same relay test on the fuel pump relay. Refer to the right side of the schematic for the corresponding pairs of contacts. One thing that I see in the schematic that also get a feed from the ECC relay output besides the fuel pump is the A/C WOT Cutoff Relay ???? I don't know what that is right now but my guess just from the sound is that it has to do air conditioning and I put my money on that guy....:)

Hope it helps.