Alternator or battery..? - Third Generation F-Body Message Boards

haxmire · 05-07-2007, 05:20 PM

Recently I got an 87 305 Carb for myself. Well I was driving the other night and it died on me with my headlights and radio on. Well I found that I had a blown fuse and found a wire which looked like was giving me a bad ground. I replaced the fuse and wrapped the wire and all seemed to be fine. The car did not bog down and want to shut off with the lights on going up my street.

So last night I was going to have to run to the store and decided to take the Camaro because it was a nice night and I already had the T's off. Well I was going up the street and had my lights on and it started to bog down and wanted to kill the engine on me again. It didn't but I didn't want to risk it and keep going.

I was wondering what could be causing this? Is it a bad alternator or battery or what? The alternator in the car is brand new. I checked the batter voltage and it was good. I guess the alternator could have a flaw. Any ideas would be good.

This ad is not displayed to registered members.
Register your free account today and become a member on ThirdGen!

1988CamaroSC · 05-07-2007, 05:22 PM

doesnt sound like either, whats your voltage read when crusing down the street? if its 13-15 its not either.

haxmire · 05-07-2007, 05:25 PM

Quote:

Originally Posted by 1988CamaroSC

doesnt sound like either, whats your voltage read when crusing down the street? if its 13-15 its not either.

the gauge jumps around when some electronics are on actually. when my blinker is on it moves up and down :/ but it is between 12-15ish

j dezzy · 05-07-2007, 05:52 PM

I had a simillar problem with my 84 TA. I'd be sitting at a redlight or something at night with the lights on, then suddenly the rpms would drop, all the lights would dim...turned out that my alt was bad. you could take it to autozone and have it bench tested. only takes a few minutes.

Toehead · 05-07-2007, 06:25 PM

If you have a DMM, you can test the alt yourself.

Let it warm up (some alts get worse when hot) and turn on most of the electronics in your car. Then, take a voltage reading aross your battery. It should be over or around 14 volts.

Next, switch the multimeter to AC volts and take a reading. You should get practically nothing. If you get any substantial voltage (1 volt or over), you might have a bad alternator diode that is letting some AC through.

The stock gauge is too inaccurate to trust. Don't use it, go by what the multimeter says. My stock gauge in my truck reads 18 volts when it is actually 14!!