3g at a loss

Austin86250

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so my 86 f250 stopped charging the other day don't know if it was the alternator or the regulator didn't care I've been itching for a 3g for a while anyway as I've done 2 swaps before I thought this would be no issue but i was wrong and cant get anything other than 12.83v

I used a 130 amp alternator part #R111719A from o riley
green to 12v key on from the old key on wire for the old regulator
yellow to charge post
white to the provision next to the connector
for the charge wire I used 4 gauge with a 175 amp fuse strait to the battery

first thought was I wasn't getting proper ground so I took both alternator brackets off and got them to bare metal to no avail
next thought was alternator was bad out of box so I pulled it and got it bench tested and it gave the green light
next thought was bad batteries even though there a year old I had a 6 month old battery drop a cell, driver side battery good passenger battery was good but needs recharge

interesting note the 2 times it died and and I needed a jump it wouldn't take a jump what so ever just got two revolutions had to pull start but it takes charge from a battery charger no problem

I used non-insulated butt connectors and marine grade heat shrink and for charge wire I used solder I verified continuity though all connections

positive cables are new as of last year negatives are cracking but I see clean copper though cracks and cranks fast as hell when charged

I'm just at a lost hear can anybody shine some light?
 

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The_Josh_Bear

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Doing a quick search after looking at your pictures, I found this 3G wiring diagram.
Have you verified that the green wire is getting good 12v with the key on? On my 3g conversion the OE wire ended up cracking on me an I chased that ghost for a while...

Also, you have the yellow wire going to the alternator output, but it should be on the starter solenoid or a battery +. It would probably still work the way you have it, but it's better the other way. I did see a diagram of the 90amp alt wired the way you have it, so it should work OK still.

Parts stores don't have good testing equipment for alts in my experience. Unless they gave you a printout with the amperage it put out under load it's possible for the alt to "pass" but not be any good. Been there, done that! :bail
 

Austin86250

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Doing a quick search after looking at your pictures, I found this 3G wiring diagram.
Have you verified that the green wire is getting good 12v with the key on? On my 3g conversion the OE wire ended up cracking on me an I chased that ghost for a while...

Also, you have the yellow wire going to the alternator output, but it should be on the starter solenoid or a battery +. It would probably still work the way you have it, but it's better the other way. I did see a diagram of the 90amp alt wired the way you have it, so it should work OK still.

Parts stores don't have good testing equipment for alts in my experience. Unless they gave you a printout with the amperage it put out under load it's possible for the alt to "pass" but not be any good. Been there, done that! :bail
I planned on running the 12v key on to my fuel pump relay that’s key on 12v to eliminate that,
As for the yellow wire I’ve ran 2 other 3g’s that way and they got 14.4
Since my charge wire goes strait to the battery I don’t think that would make a difference?
 

The_Josh_Bear

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I planned on running the 12v key on to my fuel pump relay that’s key on 12v to eliminate that,
As for the yellow wire I’ve ran 2 other 3g’s that way and they got 14.4
Since my charge wire goes strait to the battery I don’t think that would make a difference?
Sounds good.

I think it's a pretty minor difference where the sense wire is. 14.4v is solid so I would be happy with that, too.
 

CDX825

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Need to verify with a volt meter you are getting 12 volts on the green wire. Also need to see what your voltage is when its running.
 

Austin86250

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Parts stores don't have good testing equipment for alts in my experience. Unless they gave you a printout with the amperage it put out under load it's possible for the alt to "pass" but not be any good. Been there, done that! :bail
You where right got it tested at a real alternator shop failed I got it warranties now I’m getting 13.8 kinda weak but good enough
Thank y’all!
 

Booyah45828

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Good to hear. My experience is also that those cheap alternator testers aren't good. They can catch some things wrong, but you need a real one with a carbon pile and an experienced operator in order to test them correctly.

TBH I wouldn't be satisified with 13.8 either. Sounds like o-reillys got a bad batch of voltage regulators. You can swap them out easy enough if you want to try.
 

Black dawg

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See very few charging systems charge 14.5. I bet it keeps the voltage up good under load, that is what matters.
 

Austin86250

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TBH I wouldn't be satisified with 13.8 either. Sounds like o-reillys got a bad batch of voltage regulators. You can swap them out easy enough if you want to try.
i still need to clean up where the fuel filter bracket attaches to the head before i go any further
 

tradergem

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Maybe you could run a ground cable from the alternator case to the battery ground? That's what I did when I converted my truck to 3G.
 

Austin86250

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Maybe you could run a ground cable from the alternator case to the battery ground? That's what I did when I converted my truck to 3G.
that's what I'll be doing if cleaning fuel filter bracket doesn't work.
 

Black dawg

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I wouldnt be surprised if hooking the voltage regulator wire closer to the battery would get you a little higher voltage. What is your voltage drop from alt pos post to the battery pos post?
 

Austin86250

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I wouldnt be surprised if hooking the voltage regulator wire closer to the battery would get you a little higher voltage. What is your voltage drop from alt pos post to the battery pos post?
I didn’t check that, I’ll will do tonight but with it being 4 gauge I’m
Hoping very minimal
 
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