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Old 08-16-2015   #1
Kevs87ta
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GTA Year: 1990
GTA Engine: 350 TPI Automatic
Voltmeter dropping

I had the GTA out on Friday night and I noticed that my voltmeter drops almost to the red when I had my AC and fog lights on. Now I am running a March pulley system. So I was wondering if this is normal? The gauge goes up again under acceleration but as soon as I let off it starts dropping again. I was thinking that maybe it's the voltage regulator in the alternator . If I turn all accessories off, it is better but still drops a bit. Any thoughts?
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Old 08-16-2015   #2
rhomanski
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: Voltmeter dropping

Replace your alternator. It's on it's way out.
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Old 08-27-2015   #3
Kevs87ta
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GTA Year: 1990
GTA Engine: 350 TPI Automatic
Re: Voltmeter dropping

Ok, so I picked up a new alternator and it is still dropping at idle, doesn't go into the red, but it still bothers me. Is it possible I have a bad ground somewhere? I recently fixed the ground wires on the fog lights as they were corroded. So now my fogs are working properly, so could that be reason the volts are dropping, that and the under drive pulleys? Under normal driving conditions it sits right where it should be, come to a stop and then it slowly starts sinking.
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Old 08-27-2015   #4
rhomanski
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: Voltmeter dropping

Under drive pulleys. Yeah that can cause a problem. I didn't realize that's what March pulley system meant. I've never used them myself, but it stands to reason, you would have lower volts at idle and maybe less cooling from the AC and more heat because of the water pump turning slower. The slow sinking is probably because of the battery discharging.

I had one quit charging in Birmingham once. It got me to Carrolton Georgia before the headlights went out and the motor died. That was in a Dodge. Cost me $12 for the brushes and 5 minutes to change them. The battery charged up enough to start the motor. I was so happy.

Anytime you change something from stock you are going to cause a problem somewhere else. A friend told me once if I wanted more power, just put a 400 in it. I started thinking about having to reprogram the computer or lose all the gas mileage and control and swap to a carb. In the end I kept my 350. Sure, maybe a six cylinder can beat it today, but it's still pretty quick. Like me it is what it is.

Sorry about missing that under drive pulley thing. I'm guessing you'll have to live with it or go back to stock. A higher amp alternator might keep the amps up but the voltage would still probably drop. Unless somebody else has a solution...
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Old 08-27-2015   #5
Kevs87ta
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GTA Year: 1990
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Re: Voltmeter dropping

No problem, I was thinking that it was probably the problem. My alternator was 5 years old anyhow, the shop checked the it and it checked out ok. I bought a new one anyhow. Would like a chrome one for the appearance , but they aren't too common around here. It would have to come from the U.S. So maybe if I have time I will look while I am there
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