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Gas gauge

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by '73 K5, Apr 25, 2001.

  1. '73 K5

    '73 K5 1/2 ton status

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    Is there anyway with a volt/ohm meter to benchcheck a gas gauge and see if its fried??? What about checking the wire from the sending unit...what should it read?

    '73 K5
    Chevy good...Ford bad
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    A GM gas gauge is a 0 ohm empty and 90 ohm full unit. I am not sure how you check this, but that is how they are listed when you go to buy aftermarket gauges..

    Mike - <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>[​IMG]
    <P ID="edit"><FONT SIZE=-1>Edited by Emmettology 101 on 04/25/01 12:31 PM (server time).</FONT></P>
     
  3. prjt_blzr

    prjt_blzr 1/2 ton status

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    you can check the sending unit easily with an ohm meter. The sending unit should vary resistance to ground from 90 ohms to 0 ohms. Put one end of the ohm meter to ground and the remaining lead on the sending unit wire. It should read somewhere between the stated 0 - 90 ohms. If not the ground to the tank is bad or the sending unit is bad. So buzz out the ground to the tank and you now have solved the question of what is bad.
     
  4. '73 K5

    '73 K5 1/2 ton status

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    Cool, thanks for the advice. I had a new sending unit installed a couple years ago but my gauge still didn't work afterwards. I asked the mechanic about it and he said that everything from the tank up to the firewall was fine...so if he's right then its either a bad gauge or some wires are jacked up behind my dash. Good idea about the ground wire though...maybe he didn't hook that back up or something.

    '73 K5
    Chevy good...Ford bad
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    If you disconnect the ground, I believe the reading should be over full. Easiest thing to check is grab a spare gauge from the wrecking yard, (if yours are as close as mine are to me) and swap it. If that doesn't solve it, then start on the hard stuff, tracing gauge wires and such.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  6. prjt_blzr

    prjt_blzr 1/2 ton status

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    Another easy check that I didn't mention would be to go radio shack and buy a 43 ohm resistor. Connect this to ground and the gauge and disconnect the factory sending unit. The gauge should read close to half full or is that empty???
     

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