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I forgot, tried searching, Fuel gage goes crazy???

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Burt4x4, May 17, 2005.

  1. Burt4x4

    Burt4x4 3/4 ton status

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    I know we have talked about this before.

    I replaced the fuel gage when I did my Autometer swap. I replaced it with an OEM from ChevyDuty. Now the gage seamed to be working then WAM it goes all the way to the right, floats around a bit then reads fuel then WAM it goes to the right.....WTHeck???
    Is it shorting out or a loose connection?
    Any Ideas?
    Thanks
    Burt
     
  2. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    I don't know off hand but i think the gas gauge will be pegged full if the circuit is open, and pegged empty if the circuit is grounded. Maybe someone can chime in which way the gauge goes for ground/open.
    The sending unit is just a variable resistor that gives you a reading somewhere in between.
    So if opening the circuit makes the gauge read full, i'd guess you have a loose connection if its bouncing around from the reading to Full. :confused:
    (if grounding the circuit makes the gauge read full then your wire is shorting to ground.)
     
  3. spearchucker

    spearchucker 1/2 ton status

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    If there's tarnish on the windings of the rheostat on your sending unit it can do that. If you take the sending unit out you can check it with a ohmmeter by moving it through it's range, it may have some dead spots. You can try cleaning the windings off instead of buying a new unit.
     
  4. Burt4x4

    Burt4x4 3/4 ton status

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    Thanks boys
    Ya the sending unit is fairly new but it did sit fer a year. I took about 10gal of old gas out too so maby that has something to do with it..I'll check the wire.
    Like you saiid RB I too can't remember which way it goes grounded=full or empty....I'll mess wit it :D
     
  5. Yukon Jack

    Yukon Jack 1/2 ton status

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    On my gauge when the ground was off the sending unit it would go all the way to the right. Got the ground hooked up again and read properly again.
     
  6. Burt4x4

    Burt4x4 3/4 ton status

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    Cool YJ! That is what mine is doing so I thik it is loose :D
     
  7. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Burt,

    Since you did the same gauge setup I did....I can tell you that it's REALLY easy to get a short on the backside of the gauge where the clamps secure the individual gauges to the bezel.

    I used solder and shrink tube and was VERY careful and still ended up with an accidental short from the sender wire to that bracket. It only took a minute to fix, but it reminded me what a pain electrical stuff can be, even when you're careful....

    :cool1:
     
  8. Burt4x4

    Burt4x4 3/4 ton status

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    I hear ya Greg, I too used shrink wrap and lots of zipp ties. I also used a 16pin plug/connector so it is super easy to pop out my cluster and look see if it is the back of the gage or if-N it's the tank/sender :D
    hope all is well out there for ya :D
    Burt
     

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