Is my altenator going bad? Is it the voltage regulator in the altenator that is failing?

CAR = 94 GSR with 115,000 miles

PROBLEM IN THE BEGINING = cranks but does not turn over the first try. It will turn over the second time. This is an intermitent problem.

PROBLEM NOW = while driving and at idle, the tach needle drops below 500 rpm and then jumps up over 550 rpm, In addition, the headlights are dim then brighten up when reving the car at idle.

Recently at a stop light the car sputtered and died. It restarted after the first turn
of the key. Then it sputtered and died a 2nd time at another stop light and restarted
after the first turn of the key.
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- I tested the battery with a voltmeter and I get 12.78 volts with the car off. I tested
the altenator by connecting the voltmeter to the battery and with the car idling I get 14.63 volts.
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- Altenator, starter, fuel pump, fuel pressure regulator have never been replaced.

- The battery is 2 years old.

- I have replaced: coil, ignitor, main relay = these parts failed awhile ago

- Distributor cap and rotor, sparkplugs, ignition wires have been replaced as routine maintenance.

- Fuel filter = just changed it.

- Fuel Pump = has not been replaced but I hear it prime when I turn the key to the 1st position.


Modified by nb0 at 7:56 PM 6/12/2007


Modified by nb0 at 12:27 AM 6/17/2007

 

My first guess is alternator... Your lights dimming may be because of the lack of charge to the battery I would say...

 

yea almost the same problem happens with mine, except my car never dies. But somes times at idle is i just tap on the gas pedal it will go up but then go down below 500rpms and it whines somestimes. I can hear it going do wn the road and it gets really annoying?

 

Probably the alternator.

 

Starting problem is resolved. I took out the altenator and had it completely rebuilt at a reputable altenator shop. Altenator shop said the altenator was still good at 15 volts. But before rebuilding the altenator it was had to start the car; now I don't have a starting problem with the rebuilt altenator.

I tested the rebuilt altenator by connecting the voltmeter to the battery and with the car idling I get 14.4 volts.
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Idle problem: At idle, the tach needle drops below 500 rpm and then jumps up over 550 rpm, In addition, the headlights are dim then brighten up when reving the car at idle.

Idle problem solved by unbolting and cleaning IACV with carb cleaner.




Modified by nb0 at 8:33 PM 6/26/2007

 

something is probably drawing to much power, do you have an aftermarket sound system, alarm or other electrical components that could have a short or drawing too much power? I had a bad sunroof relay kill my battery over a few hours.