Dead Electrical

BrileyR

Member
Aug 29, 2021
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1
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50
Columbus, OH
Hello all. My first post is not a good one. I have an 85 GT HO, FAST EFI, 5 speed. At this moment, the car is completely dead, no electrical at all. The battery is charged. All fuses are good, and the one fusible link I can find with a yellow wire has power on both sides.

Let me explain what happened. I installed a new fuel pump, started the car to confirm everything worked, she ran good for a minute or so, I then shut it off, and started a tune-up. New plugs, wires, cap and rotor. I tried to start the car, cranked fine, but would not start, sounded like it wanted to, but also like the firing order was off. I double checked the firing order, and stupid me, I had the order set for a non-HO motor, 1-5-4-2-6-3-7-8. I switched it to 1-3-7-2-6-5-4-8, but still no start, did not sound like it wanted to at all. I checked for spark, had spark. Put motor on #1 cylinder, compression stroke, and the rotor was on #1. I figured it was not getting fuel. The FAST system if it had fuel should have started. I jumped in the car, tried to start it, gave it some throttle, it started to come to life, I gave it a bit more throttle, started to run well, then the cabin light flashed bright, the wipers came on, then the car went dead, no power. I'm not even sure where to start with this. Anyone have thoughts? I'll buy the beers if you can help me. :-(

Thanks. Briley.
 
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nickyb

WAIT,you now have a pair?
10 Year Member
Apr 3, 2009
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Id check and recheck wiring you did for fast efi install. Make sure you didn't leave bare wires, that shorted.
 

BrileyR

Member
Aug 29, 2021
7
1
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50
Columbus, OH
Id check and recheck wiring you did for fast efi install. Make sure you didn't leave bare wires, that shorted.
I didnt do the install, I bought it with it on. I just replaced the fuel pump.

Just checked the ignition switch, it is tight, no evidence of separation, or burnt wires. Could it have gone bad internally?
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Yes, the switch can short inside. I'd Check for power starting at battery, you may have cooked a wire trying to start it.
The starter is made for short use time, continued cranking put a lot of heat through the wires and starter too.
 
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BrileyR

Member
Aug 29, 2021
7
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Columbus, OH
I found a pink with yellow dotted wire with 2 connectors that was dangling on the passenger side of the engine by #1 cylinder. one of the connectors looks like it has some grey charring, maybe from arching. I did a bit of research and think it was hooked up to a couple of solenoids that were part of the air injection tube that is missing. I believe it would have had switched 12v power. That could have grounded and caused the issue. I un-tapped the wire bundle on the passenger side, there I found more fusible links, There is one large link that has 2 black wires, 1 blue wire and one yellow wire coming in, those all have power, the other side has 2 yellow and 1 black with orange, non of those have power. Where can I get this link? What size? Can I use a standard fuse?

Another issue, looks like a brown/tan single wire from the alternator is loose laying on the frame rail on passenger side, anyone know where this connects to?

The joys of buying an old car!

Thanks for the help everyone!
 

BrileyR

Member
Aug 29, 2021
7
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Columbus, OH
IMG_4051 1.jpg
 

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BrileyR

Member
Aug 29, 2021
7
1
13
50
Columbus, OH
I found a pink with yellow dotted wire with 2 connectors that was dangling on the passenger side of the engine by #1 cylinder. one of the connectors looks like it has some grey charring, maybe from arching. I did a bit of research and think it was hooked up to a couple of solenoids that were part of the air injection tube that is missing. I believe it would have had switched 12v power. That could have grounded and caused the issue. I un-tapped the wire bundle on the passenger side, there I found more fusible links, There is one large link that has 2 black wires, 1 blue wire and one yellow wire coming in, those all have power, the other side has 2 yellow and 1 black with orange, non of those have power. Where can I get this link? What size? Can I use a standard fuse?

Another issue, looks like a brown/tan single wire from the alternator is loose laying on the frame rail on passenger side, anyone know where this connects to?

The joys of buying an old car!

Thanks for the help everyone!
disregard this post. the black bundle that I thought was a fusible link is only a protective cover where they soldered wires together. Not sure what I was smoking when I tested, but there IS power on both sides. UGH!! back to testing. I'll throw in the new ignition switch I just bought.

Still wondering where that brown wire goes.
 

slow84lx

clean it good before insertion
Jul 3, 2005
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Dallas, TX
The last year of a Mustang with a carb & 5-speed which some consider the best of the Fox years and someone removes the carb for an aftermarket EFI system. Wow! Unless, of course, it was originally a CFI, AOD car, in which case it was already fuel injected and easier to stay same.

Check out this post to download the wiring diagram for your car. This will be of help as you diagnose. I think you are wasting time with the ignition switch change at this point. It sure does seem like you've got an under hood wiring issue. Give the headlight switch a hard look also before you get too far into this. Too many wires run power thru that switch also and it is a common failure point. The car can do odd things when it goes bad.



Good luck!
Jonathan
 

BrileyR

Member
Aug 29, 2021
7
1
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50
Columbus, OH
Thanks for the link Jonathan. I've run across this before, but the links are dead. "404 file not found". Any other resources?

I think I've found some issues that may solve this. There is a 30 amp fuse running from the starter relay, this was probably a fusible link that went bad previously. My original testing showed continuity across the fuse which I thought was good, but tested the voltage across it, it was 12.5 on one side, 7.5 on the other. i replaced the fuse, and I have power to the car again. I tried starting again, but same as previous, engine cranks fine, but will not start, still not getting enough fuel. I gave it some throttle, it started to run, then blew the fuse again. I found some wires on the drivers side that are frayed and exposed, one of those is being used as 12v ignition signal to trigger the injectors. My thought is that as the injectors start to fire something is arching and blowing the fuse. I'm going to replace all wires and connectors that are bad, and try again. What a mess!

IMG_4054.jpg
IMG_4055.jpg
 

slow84lx

clean it good before insertion
Jul 3, 2005
227
91
38
Dallas, TX
A copy of the 1985 service manuals can sometimes be found on the auction site that will contain the wiring diagrams and voltages that should be present in testing / troubleshooting.

Addressing all of the troubled areas in your wiring will eliminate some of the problems. And needs to be done anyway.
 

BrileyR

Member
Aug 29, 2021
7
1
13
50
Columbus, OH
Well, I didn't fix one issue, but the car is running well again. I got all those bad wires fixed, new connectors, and I made sure to tape off any unused connectors from when the Carb was removed. Installed a new ignition switch, and she fired right up, and runs great! Thanks all for the suggestions.
 
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Willybill32

But at least it's tight!
Jul 16, 2019
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Thanks for the link Jonathan. I've run across this before, but the links are dead. "404 file not found". Any other resources?

I think I've found some issues that may solve this. There is a 30 amp fuse running from the starter relay, this was probably a fusible link that went bad previously. My original testing showed continuity across the fuse which I thought was good, but tested the voltage across it, it was 12.5 on one side, 7.5 on the other. i replaced the fuse, and I have power to the car again. I tried starting again, but same as previous, engine cranks fine, but will not start, still not getting enough fuel. I gave it some throttle, it started to run, then blew the fuse again. I found some wires on the drivers side that are frayed and exposed, one of those is being used as 12v ignition signal to trigger the injectors. My thought is that as the injectors start to fire something is arching and blowing the fuse. I'm going to replace all wires and connectors that are bad, and try again. What a mess!

IMG_4054.jpg
IMG_4055.jpg
A point here…the red connector next to the factory gray connector is something someone added, and it was a poor choice. Hopefully when you replaced wires you replaced that red connector. If I were you, I’d look on eBay for the EVTM (electrical Vacuum Troubleshooting Manual) for an ‘85 Mustang, and maybe the Ford factory manual set for your car.