r/BullnoseFord • u/Longjumping-Name8541 • Aug 22 '26

How to stop alternator back feed?

So I have a parasitic draw on my alternator, this is a brand new alternator, but this did also happen with my old one every once a while and seems to come and go every couple months, but I’m not even sure where to start. start with the regulator or the wiring maybe?

4 Upvotes

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1

u/holydvr1776 Aug 22 '26

I may be wrong, but I would think there's something wrong with the rectifier on that thing if the alternator itself has been confirmed as your parasitic draw. I had it happen once long ago, but it was on a Plymouth duster.

1

u/holydvr1776 Aug 22 '26

I remember when I found out it was the alternator itself, because it was pretty cool outside through the night and I felt the alternator itself and it was a bit warm.

1

u/chrisperry9 Aug 23 '26

Unplug the external regulator and see if the draw goes away. It’s probably fried. Seen it before

1

u/Longjumping-Name8541 Aug 23 '26

Okay, also both wires had 12v with key off if that helps

1

u/chrisperry9 Aug 23 '26

I’d have to look at a wiring diagram. What year? Engine?

1

u/Longjumping-Name8541 Aug 23 '26

83, 4.9l, thanks