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Alternator going bad?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BLzr4x4ngkid, Jun 24, 2001.

  1. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    I think the alternator is going bad. Every now and then, the volt guage is reading around 13. On a day that it's running right, the gauge is reading around 14V. The gauge is probably off a little. Also, the idle is down around 400rpm when it usually idles up around 1000rpm. After it runs for a few, sometimes just a pump at the pedal, it will hop up to the right voltage and idle rpm. Sometimes, it won't ever set up right and even when driving the voltage is down. The alternator is the only thing that I can think of at this point. Thanks!

    "Don't hit me with them negative waves so early in the morning." Odd Ball--Kelly's Hereos
     
  2. Itali83

    Itali83 1/2 ton status

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    I have the same prob as you with the guage reading. Mine is almost always down. But for over 2 years, I've never had a dead battery so I don't think it is the alt. It has me stumped and agrivated. if you find something that fixes it. Please tell me!!!!!! Thanks
    Ben 87 Jimmy
     
  3. Pugsley

    Pugsley 1/2 ton status

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    I think you may be right - I'd take it to the parts house and make them test it.

    I'm so poor I can't even pay attention [​IMG]
    <A target="_blank" HREF=http://pugsley.alloffroad.com>http://pugsley.alloffroad.com</A>
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    My alternator did a few weird things before it packed it in...when I was driving at night the voltage gauge would fluctuate between 13 and 18 volts with my lights going brighter and dimmer accordingly. Normal for mine seems to be around 14 to 14.5 volts runing at 2500 rpm.

    Shortly after leaving Rocko's place (with a spare alternator, thanks rocko[​IMG]) if quit working altogether. At first it looked like it just chucked the belt, but after replacing the belt it still wasn't charging anymore. I watched my guage drop from 14+ down to 8 volts over about an hour. It was still running fine *shrug* I just couldn't see anything anymore cuz the lights were too dim...

    I think you may have some stickiness around yer carb linkage. If its running at 400 RPM the alternator won't be charging worth a crap...

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  5. AussieK5

    AussieK5 1/2 ton status

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    Mines doin the same thing, I'm gunna buy a new one tomorrow. It really pays to check into this forum and see whats goin on!
     
  6. txbartman

    txbartman 1/2 ton status

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    One other thing, I have had many GM alternators go out on me as they usually suck after you replace it the first time... A sign of an alternator going bad is popping on the radio. I don't really understand why, but its true. Now this can also be the sign of a general eletrical problem. But, if you get this with your other symptoms, I would definitely have the alternator tested and/or replaced.

    85 GMC Jimmy, 305 w/TH700-NP208, 4" lift, 32X11.5 BFG ATs, 15x10 Eagles, Smittybuilt tube nerf bars and bumbers
     

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