‘87 379 bad fuel gauge or sending unit?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by mile marker 27, Nov 24, 2022.

  1. mile marker 27

    mile marker 27 Road Train Member

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    Fuel gauge quit working yesterday in my ‘87 379. Being it’s a very early model 379, it does have alot of components that are 359ish. It being turkey day and raining for the next couple days I’m taking a break from the ol gal. That said, which typically goes out, gauge or sending unit and best way to check?
     
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  3. Raffito

    Raffito Light Load Member

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    Aug 25, 2019
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    Most of the time, the sending unit goes out before the gauge does.
    If it’s a one wire at the sending unit, just connect wire to ground and see if the gauge shows full and when you disconnect it it should show empty. If it’s two wire, just jump the wires and see if gauge shows full.
    Make sure that you have power to the gauge.
     
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