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1990 F350 7.5 Alternator 1/ Inernal regulator Wiring Help please

 
  #1  
Old 11-04-2017, 11:29 AM
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Question 1990 F350 7.5 Alternator 1/ Inernal regulator Wiring Help please

1990 F350 7.5 Alternator with Internal regulator * Need wiring Help and diagram please.

Hi new member here, Need some help please..

Just picked up a 1990 F-350 4 door 7.5L off a guy who hacked the hell out of the wiring...
I knew that the truck had electrical issues, and it needed a battery, and solenoid which we picked up that day so that I could drive it home..
Walmart Everstart garbage battery BTW.. He agreed to buy it so I could hear the truck running I didn't have options it was free..

Truck started fine, ran fine with a little miss, and noticed the dash voltage was fluctuating from max to low then normal..
Got it home parked it for the night.. Went out next day, and put my multi meter on the battery. (Should have disconnected the battery when I got home)
It was reading 3.24 volts on m multi meter so I pulled the hot terminal off right away.. Tested the battery without the cable and it was at 8v+ and slowely rising 8.1v 8.2v 8.3v ect..

Started by taking off the power wire from the solenoid and removing one by one the wires on the left side of the solenoid to see what was shorting the system out..
Long story short.. Testing the battery with ignition off, and without the alternator wire hooked up the battery jumped back up to 8 volts..
With the alternator hooked up it jumps back down to 3v and keeps slowly draining. (key off)
Had auto parts store test the alternator it didn't even make the first pass, and I figured so.
Picked up a new alternator, and a new battery.. The Everstart battery was toast in one day, but they swapped it out.
Pulled out the alternator wiring harness, and I am definitely not confident that it is wired correctly, and I do not want to take a chance here..

The alternator is a 2 plug internal regulator type, and all the wires connect together to the far side of the solenoid if looking from front of truck towards the firewall, except for one green wire/red stripe wire with a small black plug that connects a little to the side and under the solenoid.
Both the alternator plugs have 3 wire connectors, and are ran together that meet at a 12 gauge fusible link that connects to the solenoid with the battery cable. Other side of solenoid just has the starter wire..
The fusible link looks pretty rough like its seen some heat..

Alternator type is an 80 amp motorcraft from napa auto parts 2133061k- Here's another reference to see an idea of how it looks 80 amp 7745-2
Mine truck does require the plug in the 2 o'clock position. Not the 10 o'clock.



Any help on this, wiring diagram, or direction would be greatly appreciated... Thanks in advance..
 
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Old 11-04-2017, 03:10 PM
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Welcome to FTE!

Looks like you have the fire prone 2G alternator that came on this vintage truck. The connector (alternator end) to the battery is supposed to be replaced anytime you remove it. It's that bad!

Basic diagram of what you have:


Many folks on this forum and others upgrade to the later model 3G used on ~1993/94 and later model trucks.

Now is the time to throw away that fire starter and go with a 3G.


Some basic info about the 3G alternator: 3G Alternator

There are dead links to the upgrade kit from the author. He left the interwebs a few years ago.

Great info here: 3G alternator FACTS (its wins agian!) - Ford Bronco Forum
 
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Old 11-04-2017, 03:11 PM
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The best thing you can do for this truck is to convert it to a 3G alternator.
 
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Old 11-05-2017, 08:47 AM
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Thank you so much for the quick responses everyone... You guys are great, and I am happy to find this forum!! This is really gonna help me out a lot here...
 

Last edited by JayBourbon; 11-05-2017 at 09:09 AM. Reason: typo
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Old 11-05-2017, 08:57 AM
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Well now I know why the terminals that are molded into the plastic on the solenoid were completely melted off, and dangling there when I looked at the truck. The previous owner said at the time of the solenoid melting the headlights, and tail lights all blew as well..

The guy that I bought the truck from said that everything happened at once when it all blew out, and melted..
The alternator that was installed on it had the plug in the 2 o'clock position and it's a 75 amp Motorcraft. I have a friend that manages my local auto parts store and he was able to warranty and swap it out for a refurbished Motorcraft 80 amp with the plug in the 10 o'clock position. (I did this the day before I posted this). Motorcraft has a lifetime warranty on this alternator BTW.. Funny thing was that the plug on the old alternator was at the 2 o'clock position, and was really hard to reach. I think that the 10 o'clock 80 amp is actually the right one.. Not sure here why their both listed for the truck, or why the plugs mount in different positions.. Is this going to effect me in any way?

So I will swap this out for the 3G alternator here very soon but I am going to roll with the new 2g 80 amp at least for a few weeks, and assess the rest of the damage before I dump any cash into this thing.

@rla2005 Now when you say "The connector (alternator end) to the battery is supposed to be replaced anytime you remove it"
Are you referring to the blue 12 gauge fusible link in the picture? Or the plugs that attach to the alternator itself the actual issue? And also please.. Can fusible links be replaced with an in line buse fuse, a slow blow fuse, or standard fuse? How the heck are they still making and distributing this 2G alternator?
 

Last edited by JayBourbon; 11-05-2017 at 09:01 AM. Reason: Correction
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Old 11-05-2017, 10:44 AM
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It's the plugs themselves that attach to the alternator. The Ford fix at the time was to hard wire the alternator without plugs.
Swapping in a 3g is super easy to do.
 
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Old 11-05-2017, 01:24 PM
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As stated, we are referring to the alternator plug.

Example of what happens:


Some more information in this article: http://www.stangtv.com/project-cars/...light-my-fire/
 
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Old 11-07-2017, 11:36 AM
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Thanks for the detailed responses and the pics again guys..

I ended up slapping on the new fire prone 2G until I go out and pick up the 3G. I found the 12 gauge fusible link at my local Napa auto parts store for $7.99 for a 10" foot roll.
Which is a great deal btw if you have priced this elsewhere..
I ended up cutting off the alternator plug. The one that is prone to burning. (pic in previous response above) and added some Napa push type connectors. I picked up a variety pack of heat shrink from Menards, and made sure to put some over the plug ends just so nothing would arch, and the connection would stay dry.

Truck runs 14.47 volts at idle now and didn't drop too bad with the heater fan max, and all lights on. I forget the reading off hand but it was well within range.
Oh btw.. None of the other wiring fried when all the lights blew.. I literally only had 1 backup light, and the top running lights plus one license plate light working after the alternator melted my solenoid, and smoked the battery.
None of the fusible links failed!! I did buy another roll of some 20 gauge fusible link to replace the others for the lights ect.. I am reading that in time they corrode, and the corrosion doesn't allow them to blow and fail when theres a big surge, or a problem... (learned the hard way)

On the 1990 f 350 7.5 xlt lariat the other fusible links are located to the passenger side of the truck and battery against the fender wall. They are all grouped together.

I am going to be hooking back up the HELLA Comet 450 brush gaurd lights when I figure out what the proper relay is (previous owner didn't have a relay on them) , and hopefully its not too much draw..
You guys have been great!
I'd like to ask another thing while I have you guys here..
Is there is anything else I should know, about this truck that needs to be swapped out or upgraded?
I am going to do a complete tune up, plugs, cap, rotor wires, air cleaner, radiator flush, trans flush, and trans filter (if it has one new to Ford trucks), and possibly timing chain. Before I get started..

Thanks again everyone.. It's been a pleasure.
 
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Old 11-07-2017, 11:29 PM
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A PMGR starter is not necessary but completely worth installing.
You will have to do a minor wiring change, but like the 3G, it's straight forward.
 
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Old 11-08-2017, 07:52 AM
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Do not waste your money on fancy spark plugs. Plain copper plugs have proven to work the best. Some folks have bumped the timing and opened the gap on the plugs, aka SixLitre Tune-up.

That came from a member on another forum. At the time it was suggested to use a hotter coil (MSD), but their QC has gone down hill. More than a few have had to walk home after installing the shiny red can of death.

Do not install a K&N hot air intake. The factory intake is actually very efficient. A fresh paper filter is all it needs.
 
 
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