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Thread: 0-90 ohm fuel sender tuning

  1. #1
    Potential Tuner
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    Feb 2020
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    0-90 ohm fuel sender tuning

    I have a 97 trans am that I swapped an LS1 into. The gauge on the dash sweeps back and forth (when full) due to using the 97 and under fuel sender. I was wondering if this is tunable to read the 90 ohm sender correctly.

  2. #2
    Advanced Tuner mbray01's Avatar
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    Dec 2013
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    Slidell, La.
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    if its sweeping back and forth while full, its likely a bad connection. the connections at the passenger foot well are notorious for problems
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
    Advanced Level Specialist
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  3. #3
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    Double and triple checked all the wiring. Things are good there. I know the ohm reading from the sender I am using (0-90 ohm) is not the same what the computer wants to see (40-250 ohm from a 99 trans am). With hp tuners there is a fuel tab for the sender and gauge but I can?t make much sense of it, or know if this is a possibility to tune. Right now I?m using an auto meter gauge and would love to have the one on the dash working without replacing the sender.

  4. #4
    Quote Originally Posted by Bacajordan View Post
    Double and triple checked all the wiring. Things are good there. I know the ohm reading from the sender I am using (0-90 ohm) is not the same what the computer wants to see (40-250 ohm from a 99 trans am). With hp tuners there is a fuel tab for the sender and gauge but I can?t make much sense of it, or know if this is a possibility to tune. Right now I?m using an auto meter gauge and would love to have the one on the dash working without replacing the sender.
    If you're trying to read a 0-90 ohm sensor from the PCM using the Fuel level input then its a very wise idea to put a 47 ohm resistor inline with the sending unit to effectively make it a 47-137 ohm sending unit.
    The reasoning behind this is the Fuel level input is actually a monitored 5 volt signal from the PCM to the sending unit. The stock sending unit was at minimum 40 ohms, with out the inline resistor when your 0-90 ohm sender unit reads full at 0 ohms it would short out the 5 volt Vref on the PCM.

    Now of course you will have to do some calibrating of fuel volume vs % tables in the fuel tab to get an accurate working gauge with 137 ohm being empty compared to 250 ohm a stock sending unit would read on empty