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Volts gauge reads low and idle drops???????? ***KIND OF URGENT***

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Can Can, May 19, 2002.

  1. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    A little problem developed from out of the blue yesterday on my 84, brothers. I started her up, let her warm up, and kicked her down. While I was waiting for the family to get in, the idle dropped abour 200 RPMs and the volt gauge needle went from 3/4s on the gauge to about 1/2 way. After about 5-10 seconds, the idle jumped back up and the gauge needle returned to 3/4s. It seems to happen approx. once every 30 seconds. The only time I notice it is at idle.

    The best way I can describe the way it feels is to compare it to when the compressor kicks on when you're using the A/C. I'm almost positive that the AC is NOT the problem, however.............../forums/images/icons/tongue.gif

    Is this a sign of the alternator/voltage regulator preparing to die? Does anybody have any idea what's going on? I'm at my father-in-law's and have to drive about 350 miles tomorrow to make it home.

    I'll check in in about an hour- thanks, brothers!!/forums/images/icons/smile.gif
     
  2. YtseJam

    YtseJam 1/2 ton status

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    Re: Volts gauge reads low and idle drops????????

    I'd suggest checking the Alternator. Put a voltmeter on the battery and turn on some accessories. @ idle you should have atleast 13.5volts.
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: Volts gauge reads low and idle drops????????

    Just so you guys know, the idle/volt guage issue occurs whether I have accessories running or not...............and once I'm driving it doesn't seem to be a problem.

    Any other ideas?
     
  4. Pookster

    Pookster 1/2 ton status

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    Re: Volts gauge reads low and idle drops????????

    Ack! I got this same problem that started 3 weeks ago after I took it through a little high water!. No ideas yet.
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: Volts gauge reads low and idle drops????????

    Is my truck gonna make it home, brothers!!!???? I have 350 miles to go and I'll be leaving at noon on Monday............/forums/images/icons/tongue.gif

    Can anyone else steer me in the right direction???? What should I be looking for?
     
  6. ntaj*ep

    ntaj*ep 1/2 ton status

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    Re: Volts gauge reads low and idle drops????????

    When it idles down, do the lights dim? Or is there any indication of a loss of current? If your real worried check it with a volt meter, like what was already said make sure you have more than 12.5 volts, over 13.5 would be ideal. If your real worried have your charging system, battery load tested.
     
  7. SkulzNBonz

    SkulzNBonz 1/2 ton status

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    Sounds like what happened to me right before my alternator took a dump.

    John
     
  8. Pookster

    Pookster 1/2 ton status

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    Yeah, you should be fine. I'd check the Throttle position sensor though. (I've yet to do it on mine). Looks like the computer is confused at what to set the idle speed at.
     
  9. GRINCH

    GRINCH 1/2 ton status

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    Doesn't seem like an alternator problem to me if the idle is dropping way down. What engine set up do you have in this? Carb, tbi,tpi....????

    I had the same thing happen when my TPS sensor went south..

    A little more info and maybe we can get this solved.
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Uhhhhhh Hmmmmm that got the electric mix control carb? I would lay odds on that. The low volt is a result of low idle most likly, not the voltage goes low on the alternator and causes the truck to idle low. The truck would run for several hours on the battery (without the lights on) before the batter droped enough charge that the engine would quit.
    As for making it home. Should be fine. I'm pretty sure the mix control only does stuff at idle. Going down the road it should run fine. Check the pulgs on the top of the carb and the control switch on the sensor behind the distributor. Also check the "Choke" fuse. It runs on the same circuit.
    If you do find it to be the carb get a carb off about a 80. Will have ALL the same connection except that stupid mix solinoid.
     
  11. txbartman

    txbartman 1/2 ton status

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    First off, he said 84. That would mean no TPS. Most likely, the only thing electronic on his carb is the idle mixture control, like Grimmy said. Also, like Grim said, the lower voltage is due to the reduced RPMs, not the other way around. That is an effect, not a cause.

    If you have an a/c, you should also have an electronic fast idle device. It is an electronic plunger that gets pushed into the throttle linkage when the a/c compressor is supposed to kick in. If you are looking at your carb from the front, it will be on the front right side. This could be shorting and working actually in reverse (meaning your normal idle has it out for higher idling and it releases when your idle drops). I have seen these be out of whack for so long that the owner didn't know and had adjusted his idle to compensate. You can easily unplug that to help determine if it is causing your idel problems (although HIGHLY unlikely). Just trying to throw EVERYTHING on the table.

    you have probably already left by now, but none of this should affect your RPM or alternator output at highway speeds. You should be cool for your drive home.
     
  12. txbartman

    txbartman 1/2 ton status

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    Re: Volts gauge reads low and idle drops????????

    Some alternators don't react well to being submerged. You may have fried yours when you did this. I also know they don't like mud. If you get one caked with mud, you have to be real careful about cleaning it so you don't cause it to fry from too much water! Catch-22
     

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