Thread: Why does my voltage drop when I got WOT

My voltage will go from 13.89+ to 10.xx and will shoot back up as soon as I let off. So far I have replaced my alternator and I still have the same problem. I plan to replace the belt tomorrow and go from there. I have checked the body ground next to the battery and the ground that goes to the trans they are ok, am I missing one?

Did you check the one that goes to the starter?

Originally Posted by slick2500

Did you check the one that goes to the starter?

I knew I was forgetting one. Ill go check it now and report back. (I thought it just grounded to the block)

to add to this, I can sit in the driveway and bring it up to 4000 rpm and its fine..

Originally Posted by slick2500

Did you check the one that goes to the starter?

I dont have a ground on my starter..

You have a ground on your starter it's a little green wire iirc. You might have belt slip or maybe the alt gets bypassed at wot?

Originally Posted by dsmuts

You have a ground on your starter it's a little green wire iirc. You might have belt slip or maybe the alt gets bypassed at wot?

Ill take another look at the started when its up on the lift tomorrow. But It can be good for the injectors to see voltage below 12v, wouldn't that cause a lean condition?

injectors never see 12v anyway I think they only see partial voltage.

The mating surfaces for the alternator is the alternator ground. I doubt that is the issue since the 3800 has a lot of mating surface for the alternator, but I'd clean that as well if you haven't already.