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Discussion Starter #1
Well my wife was driveing on the freeway and the bronco suddenly lost power.. She managed to get to the side of the road and tried to start it and it wouldn't fire..

Had it towed the my mechanic and they played with it for 3 hours before I showed up and couldn't get it running..

Well I show up and when you turn the key on the fuel pumps would not prime.. (not coming on) They checked and said there was no power going into the EEC relay..

They did show me that they could jump a wire from the coil to the harness by the injectors and the truck would start and run just fine. Well I had them put the jumper on and we brought the truck home so I could pull codes from it.. (For some reason they didn't/wouldn't do it.. I don't think they had a scanner)

Well I came home and pulled codes..

KOEO test showed
54 - Air charge temp sensor (I've had this before no biggie)
67 - (the book shows 4 different reasons for this code)
82 - (air diverter splenoid circuit fault) or Intergrated relay control manual
Continious Memory codes
54 - Same as above
87 - (Cars Only) Fuel pump primary circuit fault
96 - Fuel pump secondary circuit fault/high speed fuel pump relay open
29 - Insufficient input from the VSS or Insufficient input from programmable speedo/odo module

Well I tried jumping the power wire to the fuel pump and the fuel pumps came out but the truck wouldn't start.. I turned the key off and the pumps stayed on until I unplugged the EEC relay..

Tried pulling codes and there was only code 54 from the CM codes, but 54,67,82 did repeat on the KOEO test..

Any ideas would rule.. This is my wife's only mode of transpo.. :( Her chevy won't be out of the shop for a couple of days..

Weird thing is, but might just be a coincidence is that my wife had 1/2 of tank of gas and when this all happenend now the gauge reads full..
 

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Discussion Starter #2
That's what I'm going to check today when i get home..

I forgot to mention I had a shop change the head gasket last week..
 

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Discussion Starter #3
Steve, you quoted this on another thread..

Steve83 said:
You can go under the truck, find the Y/Wh wire at the tank, & short it to ground. (You don't have to disconnect anything.) When you turn the key to RUN, the gas needle should go to E.
Do you think the issue I'm having with the fuel gauge going to F when it only has 1/2 of tank of gas could be part of my problem?

Also if I short this wire to test it and nothing happens where should I begin to look?
 

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well i popped open the wiring diagram for your truck and thought i'd try to help you out. The first question though is where are you tapping power into?? This will help cut the troubleshooting down to whether it is the power to activate the relay or the power that the relay is used to turn on. The power to activate the relay also powers the coil, so based on a couple assumptions and the way it is jumpered to get it running im guessing it is the power the relay turns on.

First im assuming an 1987 wiring diagram, and what your mechanic found.

so based on that, check the BROWN fusible link at the starter solenoid. they are encased in solid rubber. Use a test light after it or wiggle it back and forth to see if you get any response. If no power, replace the fuse.

If no luck there, then locate the EEC power relay. The relay should be in the power distribution box on the left side of the engine compartment (4th relay down on left side-but check your manual). Hold your finger on it, and turn on the key. You should feel it click. If it doesn't click then follow step A, if it does click follow step B. (also you mechanic may have made a very general statement-swap out the relay to make sure thats not the problem).

Step A: Pull the relay and check the black wire for ground. next check the white-lt blue at the relay for 12 volts (when making power checks assume the ingition is on). If either fail i can fill you in on further troubleshooting.

Step B. Check the yellow wire at the relay for 12 Volts (this is coming from that brown fuse i said to check first). Next, the diagram shows a blue fusible link coming out of the relay, but im not sure if it is located right there or not. It should be a red wire. Check that fusible link/red wire for 12 Volts (it will only have power if the relay is installed and clicking on. (So use a test light if you can't get to the backside of the relay). If you find any failures I can help from there to trace it down.

I am guessing you tapped into that red wire somewhere to get home.
 

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Zombie Hunter
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Might want to give the Inertia Switch a once over to, but i am not sure if in your year bronco if that is before or after the relay.
 

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Bronco Rob said:
Might want to give the Inertia Switch a once over to, but i am not sure if in your year bronco if that is before or after the relay.
It looks like the inertia switch will only cause the fuel pumps to fail, but you would still have power at the eec relay. (quick look at the wiring diagram, i might be wrong)
 

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wakeav8b said:
It looks like the inertia switch will only cause the fuel pumps to fail, but you would still have power at the eec relay. (quick look at the wiring diagram, i might be wrong)
No your right, i read the initial post too fast. My bad
 

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Discussion Starter #8
Thanx for all of the replies.. Unfortunetly it's 10:30 here and I've been out all night so I haven't messed with the BKO yet.. I'm going to dedicate all day tomorrow to try and fix it and will try the suggestions.

Wakeav8b, The EEC relay is good (It's the green one if I'm correct) I took it out of my bronco and put it in the neighbors 88 and his fired right up. I can feel it clicking..

The jumper wire that was made to bring it home went from the red wire on the injector closest to the oil cap to the yellow wire that goes into the grey plug that goes to the coil. (dunno if that helps or just makes things confusing)

I used to have a manual, but Alas I left it in the engine one night and the wife decided to drive off without asking me if I was done with the bronco and well it burned up.. heh.. (this was a long time ago and the wiriing isn't burned or anything and has since been replaced..) Stupid previous owner and their crappy hack and whack jobs...

The only wiring that's different is the wires from the fuel pumps.. Instead of going from the harness they by pass the grey connector that connect the under carriage harness to the main harness and go to the brown wire on the EEC relay.. (This has worked for months) It used to go to a different power wire and with it like that I was never able to pull codes, but as soon as I hooked the wire up this way (followed color codes with the wiring diagram) It started working right and now I can pull codes.
 

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Quick reply since i'm on my way to work. Sounds like thew relay doesn't click in your truck but clicks in your buddy's truck? Also you tapped into the red wire at the injectors (which is what the relay turns on). Since the coil still has power ( you didn't jump into line), I bet the eec relay has power also-but since its not turning on--

Therefore I would check for a bad ground at the eec relay. I don't know the pin off hand, but pull the relay and check for any grounds at the terminals, if none are present theres the problem. EDIT: you could read through another relay or pump back to ground and get a false reading from another terminal, best to find the right pin.

Im not sure about how you jumpered the fuel pumps, but the eec relay is supposed to power the fuel relay

good luck :thumbup
 

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Discussion Starter #10
Well by Steve's post the green relay I'm checking is the FPR relay, which makes sense.. The voltage checks out.. So for the hell of it I unplugged the connector from the intertia switch and put my test leads into it and didn't get any voltage through the connector.. Even check for resistance and it showed a constant open..

I'm gunna go back outside and try and chase it down some more.. This wiring is ugly.. I wish it was a clean job, it would make this so much easier. :)
 

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Discussion Starter #11
Well here's a little update..

I got real irritated that the wiring was so ugly and bunched up, so I decided to untangle it all.. Well as soon as I plugged the big square black connector in the fuel pumps primed like normal but the battery is to weak to try and start it.. (and my battery charger just broke)

Figures.. So now I can't test to see if it was just a connector not making good contact.. My wife just took our other vehicle to the store so I can't try jump starting it.. (sigh)

Guess I'll go outside and fix the door locks while I'm waiting. :)
 

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Discussion Starter #12
Well the pump primes, but I still have no voltage going through the inertia switch..

Steve I looked through your site but didn't see a diagram for the fuel system.. Does anyone have one?
 

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Discussion Starter #13
I found this pic Coincidence? I just found that one of my starter bolt fell out.. On this diagram shown below it shows a wire coming from the starter to the Fuel pump relay



 

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Discussion Starter #14
I just ended up running a wire from one of the injector wires to a switch and then from the switch to the grey connector that goes to the diode that connets with the coil.. Temp fix for now. :(
 

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Discussion Starter #15
Steve83 said:
I don't think there's supposed to be a resistor between the pumps, and I think the 37Y circuit is shown wrong, but otherwise, that's the right wiring diagram for your truck.

Inertia switches are known to just go bad occasionally. Jumper across the wiring connector to bypass it.
I'm not reading power on any of the 2 wires on the inertia switch.. So jumpering it won't make a difference..

I know the brown wire goes to the relay, but there is a Red wire with a black stripe that goes up twards the fuse box, but I can't see where it goes to..

I also don't have the panel on under the steering wheel so I don't know what fuse is for what and the only pic of it I've seen is the one on your website and that's for an 83 and not an 87..

As for the fuel gauge I tried shorting the wire you stated in that post to ground, but it didn't do anything.. It still pegged at full..
 

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Discussion Starter #16
Well.. This is odd..

I changed the fuel pump and now the bronco fires up and runs without any problems..

The stupid Fuel gauge is still pegged to F.. (ya ya I know the sender is inside the tank with the pump.. But I didn't have the cash to replace that.. Plus it was working fine before the mechanic messed with it, so my wife is going to take it to them and tell them they broke it..

If not it's no big deal.. It only takes me a whoppin 15 minutes to have the whole tank dropped and out of the truck.. (I've gotten good at it) :p

Also for S&G's I decided to unplug the inertia switch while the bronco was running and it didn't do anything.. I thought it was supposed to kill the motor.. (guess it's bypassed somewhere)
 

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Discussion Starter #17
Well this morning my wife starts up the bronco and starts driving off and it dies.. So I had to put the jumper wire set up back on.. I wonder if the fuel pump in the rail is having an issue)
 

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My 89’ had a mysterious problem similar to what yours does. I did not read all the posts, so I may be off track, but here it is anyway.

After many episodes of just dying and pulling off to the side of the road just to have it start again some random time period later, I found that the push on electrical blade type connectors on the rail fuel pump were loose. All’s I did was use a pair of pliers to tighten up the connectors, push them back on, and it never did it again. (8 years ago now)

Hope that helps.
 

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Discussion Starter #19
Well.. Here's an update

It used to start with the jumper wire but it died again.. I had to run a constant power from the battery to the fuel pumps and it fired up, and then I get it home and it just doesn't want to start..

The only way I've gotten it to start is to jumper both big posts on both the fuel and eec relays...

help! :(
 

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Discussion Starter #20
Also.. I can not pull codes from the ECU unless I jumper the big posts on the EEC relay.. :(

I did get a code 87 which my book says it is the primary fuel pump system failure. Which I don't know what could cause this..

Are there any fuseable link or something I could be missing?
 
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