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Fuel Sending Unit Works Outside of Tank But Not In the Tank

Electrical and Ignition

  1. money pit

    money pit Well-Known Member

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    I have a 70 Barracuda. My gas guage reads a quarter to a half a tank after I fill up. Up to this point it was working fine. I tried replacing the sending unit (an OER unit). The same thing happened. I have a ground to the sending unit, directly from the battery. I tried both sending units outside of the tank, both seem to work fine. When I place the units back in the tank, they read the same as before. I checked the sending units with an Ohm meter, it's within specs. I know the guage works, I grounded the lead, it pegs the guage. Could there be something in the tank that is interferring with the sending unit? I read about the same problem on a number of forums but no difinitive answer. This is driving me crazy. Thanks
     
  2. 69hemibeep

    69hemibeep Well-Known Member

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    See if you are getting a full 5 volts past the limiter on the cluster. I had two from Redline that were 4.5 volts which equaled almost 1/4 tank
     
  3. money pit

    money pit Well-Known Member

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    I'm not familiar with the limiter you are speaking about. Where is it located on the cluster? Also, could my temp gauge be causing this problem? I read in a couple of forums that sometimes the temp and gas gauge have problems at the same time. I'm not using my stock gauge. Electrical issues isn't my thing, that's why I'm getting frustrated. Thanks again
     
  4. tonysrt

    tonysrt Well-Known Member

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    Also make sure your tank is grounded. Gauge won't work without ground.
     
  5. money pit

    money pit Well-Known Member

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    I have a ground directly to the battery. I check to make sure I Have a pulsing voltage at the wire that connects to the sending unit. Thanks
     
  6. 69hemibeep

    69hemibeep Well-Known Member

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