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Fuel guage problem... sender or guage?

Discussion in 'The Garage' started by txbartman, Jun 6, 2002.

  1. txbartman

    txbartman 1/2 ton status

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    Ever since I bought my truck, the gas guage has never worked right. When the tank is full, the guage is on 1/4 tank. When it is empty, it sits about 1/16 inch below E. And, it appears to move in a relative rate in that range. Kind of like it is just operating on a much smaller scale.

    How can I determine if it is the guage or the sending unit? I don't think its the float in the tank as it doesn't sit on 1/4 for a long time and then drop. It starts dropping immediately when I start eatin' up the gas.
     
  2. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Your fuel gauge works off of resistance. The sending unit provides a range of resistance from 0 to 90 ohms. The best way to check the sender(without removing it from the truck) is to measure the resistance level when the tank is full and then measure it when it is empty. If you are getting a full 0-90 ohm range then the sender is good and the gauge or the wiring in between is bad. Hope this helped!

    Mike
     
  3. txbartman

    txbartman 1/2 ton status

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    Thanks. I'll start with that. I had no idea what the "right" values were. I have a meter that measures resistance, but have never used it for such. I only have experience using it to measure voltage. How do I measure resistance? of course I set the meter accordingly, but what to I attcah the leads to? anyone know what wires coming from the tank I could tap into under the rig versus having to get into the gauge cluster?
     
  4. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    If I remember correctly the wire going to the sender is orange. Set your multi-meter to read resistance and ground one lead to the frame and the other to the wire. That will give you the resistance reading.
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Also if you remove the sender wire and ground it to the frame the gauge should read full, or above full. If it does not read at least to the full mark the gauge is bad.
     
  6. chulisohombre

    chulisohombre 1/2 ton status

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    i have the same problem but the guge show 1/4 all the time.i plugged in an extra guage cluster to the harness and th needle didnt move then either so should to check the float is there 1 or two wires because i only see one coming up into the harness from on top of the tank
     
  7. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    There is just one wire.
     

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