Help with the charging system in my brother's truck?

[poweredbyford1]

Looking at my brother's 1990 F-250 7.3

He pulled the cab and front clip off to paint / rustproof / better slap a turbo kit on it, and since he's put it back together, it won't charge. He's replaced the voltage regulator and the alternator already.

Checking battery positive to alt case shows it's not a ground issue, but there's a twist.

Someone somewhere in this truck's life cut the yellow wire that goes to the "A" pin on the regulator. Couldn't figure out why until i tried putting it back and now it WAY overcharges, almost to 18 volts.

So, it acts the same as when you just pull the pigtail and jump the "A" and "F" pins. Balls to the wall full field at all times. Thing is, regulator is a new reman, he said no one has factory Ford anymore.

I told him go to NAPA and get the best brand he can find brand new, not reman, and to cut that pigtail off going into the regulator, cause it's full of green crust and rust. If, once the regulator and pigtail are new it's still overcharging, what do I do next?

The pics attached are from the fender well on the other side of the truck. The only charging system wire i can think of that goes that way is the one for the battery light, which works. But what are these plugs, and do they have anything to do with the charging system? I don't think so, but an ID would be nice.

Thanks for any help guys

 

[IDIDIDIhoDhoDhoDO]

I think your best bet is to just get rid of that low output externally regulated alternator and put in a 3g instead. There is plenty of information and write ups on different forums on how do to the upgrade if you search for '7.3 idi 3g alternator upgrade'.

It was one of the best upgrades I did for my truck. The old 1g alternator wouldn't even keep up with headlights when at idle. You could rev up the engine and watch the dim headlights brighten up. I got a 3g alternator and the wiring harness from a junkyard and rebuilt and installed it. It was a HUGE improvement. Highly recommend.

 

[Noiseydiesel]

"...full of green crust and rust..." Sounds like you found your problem.
Electrical theory tells that electricity does not travel through the core of the wire, but on the outside of the wire. Consequently corrosion will impede this flow. Larger wires only have more surface area for flow. Corrosion is still an issue.

 

[poweredbyford1]

"...full of green crust and rust..." Sounds like you found your problem.
Electrical theory tells that electricity does not travel through the core of the wire, but on the outside of the wire. Consequently corrosion will impede this flow. Larger wires only have more surface area for flow. Corrosion is still an issue.

Yeah for some reason he didn't grab the new pigtail the other day, so i gotta wait and see if that cures the charging part. Would you happen to know what any of those plugs in the pics are?

 

[poweredbyford1]

I think your best bet is to just get rid of that low output externally regulated alternator and put in a 3g instead. There is plenty of information and write ups on different forums on how do to the upgrade if you search for '7.3 idi 3g alternator upgrade'.

It was one of the best upgrades I did for my truck. The old 1g alternator wouldn't even keep up with headlights when at idle. You could rev up the engine and watch the dim headlights brighten up. I got a 3g alternator and the wiring harness from a junkyard and rebuilt and installed it. It was a HUGE improvement. Highly recommend.

Looking into that too. I guess there's a one wire ford alternator out there somewhere you can use as well? I dunno i saw it mentioned elsewhere on the webs. Would you happen to know what any of those plugs are and where they go?

 

[IDIDIDIhoDhoDhoDO]

I looked on my truck around the driver's side fender and I found 3 plugs similar to yours but not exactly, all female, that were unplugged. I don't know what they go to, they may go to nothing. They might just be plugs that get left unused at the factory depending on what accessories get ordered or not. But that's just a guess. When I swapped a 3g into my truck though, none of the wiring for the alternator or external regulator was on the driver's side of the truck.

I am not sure about a 1 wire alternator that swaps in place of the original alternator on these trucks. When I did mine, even among the 3g alternators, you still needed a find a specific one to get the mounting ears in the right place. It was from the taurus and windstar with 3.8L engines in the 90s I believe. Not truly a 1 wire alternator, but still not a complex wiring job, but you do need the harness from a donor vehicle or a new one from eBay.

 

[poweredbyford1]

I looked on my truck around the driver's side fender and I found 3 plugs similar to yours but not exactly, all female, that were unplugged. I don't know what they go to, they may go to nothing. They might just be plugs that get left unused at the factory depending on what accessories get ordered or not. But that's just a guess. When I swapped a 3g into my truck though, none of the wiring for the alternator or external regulator was on the driver's side of the truck.

I am not sure about a 1 wire alternator that swaps in place of the original alternator on these trucks. When I did mine, even among the 3g alternators, you still needed a find a specific one to get the mounting ears in the right place. It was from the taurus and windstar with 3.8L engines in the 90s I believe. Not truly a 1 wire alternator, but still not a complex wiring job, but you do need the harness from a donor vehicle or a new one from eBay.

Gotcha thanks for helping out man!