Installed 3G alternator.....Idle is 11 volts!!

Geeq

New Member
Jun 15, 2004
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I just installed a 200 AMP PA performance alternator in my 1990 5.0

This should put out well over 12.5 volts at idle....In all reviews and installs this is shown.

Everything was installed correctly. I installed the required 4-gauge power cable and all connections completely.

Could it be my battery???.....But When the engine is off the battery shows 12 volts.....but at idle 11 volts....And my volt gauge inside the car on the gauge cluster fluctuates at idle.

The alternator was shipped to me by 50resto....in a box with other stuff and the box was beaten up. Could it be damaged?
 
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If it is installed correctly then there is probably a loose connection somewhere or you by "chance" got a bad alt. My bet whould be your connections somewhere. Double check, triple check and be sure you soldered all your joints and non of that crimping crap. Especially on that 4 gauge wire.
 
Don't discount the possibility of the factory dummy gauge being out to lunch a little too. When you bring up the RPM, does the charge quickly recover? If so, I wouldn't worry so much, it's probably working just fine.
 
Put a test light on the ignition wire and make sure you're getting voltage with the key on, simple test. It's what fixed mine when it wasn't charging. If I'm not mistaken with the car off you should be at 12v's at the posts, and when you crank the key you should be above that, in the 13-14 range. Another test would be to turn on the car, remove the negative terminal on your battery, if the car dies the alternator isn't charging, check the ignition wire; I think it's the green/red wire.

Good luck.
 
id just take the whole car to the parts store and have them test it (in the car). you can do bench tests later, but it might save you some wrenching and time.

did they recommend a 4 gauge cable for a 200 amp alt? i might have gone with an even fatter AWG wire (im just curious).

good luck.
 
Well I pulled it and had it tested....it is charging.

I did triple checked my connections and everything is perfect.

I keep getting low voltage at idle. I raised my idle and it helped a little....but over time I still get problems at idle. The gauge fluctuates.

My lights dim when I'm at idle too....Everything dims....This should not happen with the 200amp alternator. This is BS.

Car has a new battery so this is not the problem. I'm at a loss.
 
What are you running for pullies? Also double check to make sure they sent you the correct alternator. I was reading up on alternators a couple of days ago because I need to upgrade mine, especially since I put on the electric radiator fan....I'll try and find some of the stuff I was reading up and post my findings as soon as I can...good luck.