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Thread: 91 Silverado Problem. Need advice.

  1. #1
    Join Date
    Oct 2012
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    Default 91 Silverado Problem. Problem solved.

    So here's whats going on. The battery went dead a few weeks ago. I put the battery on the charger and it wouldn't hold a charge. No problem, went and got a new battery. Put it in the the truck and it cranks good, idles fine, then when I take off down the road the gauges start jumping all over the place. Radio and AC start cutting in and out. The voltage gauge spikes all the way over when you hit the throttle. So I turn around and limp back to the house thinking my alternator is bad. Put a new one on and it didnt help. If anything its worse. It idle's pretty good in park but if you put in drive, the gauges start jumping and the engine starts idling rough. Can anyone give me an idea where to start looking for the problem?
    Last edited by luckydogger; 06-05-2018 at 07:36 AM.

  2. #2
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    sounds like a bad voltage regulator to me but I'm no mechanic.
    Bone....

  3. #3
    Join Date
    Dec 2010
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    5,189

    Default

    There may be an in-line fusible link in the wire leaving the alternator, maybe a few inches from the lug that hooks to the alternator. If it's blown it won't allow the alternator to charge and do what it's doing now.
    Looks similar to this,
    FUSIBLE-LINK-NON-NASCAR.jpg

    Or, look for a blown fuse in you fuse panel(s).
    Last edited by Bownut; 04-23-2018 at 11:18 AM.

  4. #4
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    Quote Originally Posted by HERRINGBONE View Post
    sounds like a bad voltage regulator to me but I'm no mechanic.
    If I am not mistaken, the voltage regulator is inside the alternator.
    Start with the easiest first, check battery cables all the way from battery to the starter and the ground cable from battery all the way to the block.
    Then check plug from the back of the alternator and follow it.
    I would crank truck and see if it will stay running with battery unhooked.......if so, problem is not with alternator most likely.
    Last edited by ecu1984; 04-23-2018 at 11:21 AM.

  5. #5
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    Go buy you a good alternator and replace it.
    More fuel = more boost!!

  6. #6
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    Quote Originally Posted by KRT View Post
    Go buy you a good alternator and replace it.
    this is what I was thinking. Go get one from a reputable auto parts store like Napa...not Advance or Auto Zone. I'm not a mechanic by any means but have seen several bad alternators from the A's. Kind of like buying GFCI's from Lowe's. Every third one will be bad.

  7. #7
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    Could there be an issue in the wiring harness? Had an 89 Ford Ranger that would idle well and drive good, but going down the road it would drop RPMs and pop and skip. Found a broken wire going to fuel pump. Turn truck on and just shake wires and see if anything happens. Just a thought. Good luck.
    Psalm 42:1 "As the hart panteth after the water brooks, so panteth my soul after thee, O God."

  8. #8
    Join Date
    May 2015
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    Is it an internally or externally regulated alternator? Is there 1 wire coming off the alt. or a plug with multiple wires? If its externally regulated i'd say it sounds like a voltage regulator issue. Sounds like its producing 12-14 volts at idle, then the voltage spike with RPM.

  9. #9
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    Shoot it repeatedly in the grill with an AR and it should run like a scalded dog after that

  10. #10
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    Oct 2012
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    Quote Originally Posted by lowbudget View Post
    Is it an internally or externally regulated alternator? Is there 1 wire coming off the alt. or a plug with multiple wires? If its externally regulated i'd say it sounds like a voltage regulator issue. Sounds like its producing 12-14 volts at idle, then the voltage spike with RPM.
    I believe it is internally regulated. There is one stud on the back that has the big wire bolted to it and then there is a plug that clips to the alternator. It only has one wire, and not multiple wires.

  11. #11
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    Quote Originally Posted by reeltight View Post
    this is what I was thinking. Go get one from a reputable auto parts store like Napa...not Advance or Auto Zone. I'm not a mechanic by any means but have seen several bad alternators from the A's. Kind of like buying GFCI's from Lowe's. Every third one will be bad.
    I think the one I put on there is a good one. I cant remember the brand right off.

    KRT- What brand would you say is a good one?

  12. #12
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    Quote Originally Posted by luckydogger View Post
    I think the one I put on there is a good one. I cant remember the brand right off.

    KRT- What brand would you say is a good one?
    the kind he sells

  13. #13
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    Oct 2012
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    Trying to post a video
    Last edited by luckydogger; 04-23-2018 at 06:40 PM.

  14. #14
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  15. #15
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    So I finally got a chance to work on this truck. Turns out it was just a ground strap from the block to the frame had come loose. Reattached it and am back in business.

  16. #16
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    Haha

    Not laughing at you. Grounds will gitchy.
    Last edited by CurLee; 06-05-2018 at 09:03 AM.

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