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Alternator losing voltage with high boost

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Old 07-27-2018, 12:45 AM
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Default Alternator losing voltage with high boost

I keep getting voltage drops from my alternator when I have my truck making a little steam. Every time it seems to be right around 5800rpm it drops to about 12.0V. In turn it is dropping the voltage to my Meth system and it goes lean for about 1sec until the shift. I tried a new alternator because I was thinking the brushes were worn. And it did seem to clear up. The new 145amp alternator now has about 1200 miles on it and just had the same issue at the track last weekend. Had the truck turned up to about 18psi. Doesn't seem to drop voltage under 15psi. I don't see alot of belt dust around the alternator like it could be slipping. Doesn't mean that is not it.

Before I go buy another alternator and a gatorback belt. Any thoughts? Ideas? Both Alternators were acdelco units.
Old 07-27-2018, 11:41 AM
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When does your second pump kick on? Could it be something to do with that?

I would imagine going lean is more than just the meth. It would effect your primary fuel system as well. Fuel pumps flow less and injectors act different as voltage drops.
Old 07-27-2018, 11:45 AM
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Originally Posted by Vortec350ss
When does your second pump kick on? Could it be something to do with that?

I would imagine going lean is more than just the meth. It would effect your primary fuel system as well. Fuel pumps flow less and injectors act different as voltage drops.
I'm sure your correct. It would effect way more than just the meth. My second pump kicks on at 7psi. So I'm pretty far into the dual pumps running. Weird thing is this went away for a little while with the new alt. Maybe the new one is wearing out already?

You spin your motor way above 6k don't you? Have you ever had Alt issues with higher rpm?
Old 07-27-2018, 12:10 PM
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I never had issues, I hit 7
Old 07-27-2018, 12:12 PM
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I did, and I do now as well, but I haven't had this combo running for long. I have not had issues with voltage.
Old 07-27-2018, 07:30 PM
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Ok. I'll go buy another new Alternator.

What is the best belt out there to get anymore? I always just buy a gates belt. Goodyear Gatorback worth the money?
Old 07-27-2018, 09:18 PM
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Have you upgraded any of the wiring? I'd do a big 3 upgrade before replacing the alt again.
Old 07-28-2018, 12:22 AM
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Originally Posted by BudRacing
Have you upgraded any of the wiring? I'd do a big 3 upgrade before replacing the alt again.
i actually haven’t done this upgrade yet. I kinda forgot about it. I will get on this upgrade this week and see if that changes things. Good thinking! Thank you for the input!

Ill look it up. But isn’t it 4 wires? 3 grounds(battery, alt. bracket and chassis grounds) and the alternator to battery power wire?
Old 07-28-2018, 01:40 PM
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New or rebuilt alternator? I recommend new.
Old 07-28-2018, 02:04 PM
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Originally Posted by MikeGyver
New or rebuilt alternator? I recommend new.
First one was a reman. The second one was a new ac Delco.


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