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1992 Chevy Truck Alternator

Tiny
JGCF57
  • MEMBER
  • 1992 CHEVROLET TRUCK
Electrical problem
1992 Chevy Truck V8 Two Wheel Drive Automatic alot miles

This truck has a new battery and alternator. At idle, the dash gauge reads 14v. With the headlights on but when I rev. The engine the voltage drops to 9v. And the lights dim noticeably. What's up with that? I know you guys don't like life-time warrantied alternators but they said it tested fine. What do you think?
Thanks for your help.
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Thursday, May 29th, 2008 AT 10:54 PM

4 Replies

Tiny
PEAR69
  • MECHANIC
  • 1,482 POSTS
Check the voltage regulator. It does sound like a failing alternator.
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Friday, May 30th, 2008 AT 3:13 AM
Tiny
PEAR69
  • MECHANIC
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Check all the grounds too.
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Friday, May 30th, 2008 AT 3:13 AM
Tiny
JGCF57
  • MEMBER
  • 8 POSTS
This sounds logical. However, since the old guy who owns the truck changed his fuel supply the problem went away. I said "bad" gas has no electrical effect on the fuel injectors and the current draw on injectors has little to no effect on headlights but until he empties the tank and refills with the "bad" gas to "prove me wrong", I can do nothing. I believe what I told him was true and I will let you know what happens. Thanks for your help.
Jgcf57
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Saturday, May 31st, 2008 AT 10:04 PM
Tiny
PEAR69
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Hmmm, bad gas causing a voltage drop--interesting, very interesting----please get back to me on this one----please.
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Sunday, June 1st, 2008 AT 4:16 AM

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