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Fuel issue - 99 Tahoe LT

Discussion in 'Engine & Drivetrain' started by Guitarded, Jun 5, 2020.

  1. Guitarded

    Guitarded TYF Newbie

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    Did a search, haven't found the answer to this issue.

    From all the research I've done, it appears that a 1999 Tahoe 4-door should have a fuel tank of roughly 112L.

    When my fuel gauge is reading just under 1/4 tank, I fill up, and it only takes about 50L until it's full.

    So from what I can tell, the fuel gauge is treating a half tank like a full tank.


    What could be causing this? I'm guessing the float or fuel sender, or whatever it is in the tank that measures the fuel level just isn't working properly.

    On the plus side, my old Tahoe is getting better mileage than my new truck.
     
  2. exp500

    exp500 Full Access Member

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    There is alot of Diagnostixs to do to properly Fix the old girl. Check grounds first, expecially at the fuel pump. Was the pump recently replaced? Setting ANY codes? On this vintage the last 1/2 tank goes fast compared to 1st 1/2. Yes, your sender is suspect, so is dash gauge. Do you have any resistors laying around? you could feed power thru 75 Ohm resistor(s) to check dash guage from rear.
     
  3. liquify33

    liquify33 Full Access Member

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    What does the gauge show when you fill it up? Do/did you have a dancing fuel gauge?


    Since you say it’s running well I’m leaning to instrument cluster vs tank issues but there are way to verify before throwing parts at your truck. Even a cheap OBD reader can show the voltage input from the tank fuel level sensor
     
  4. Guitarded

    Guitarded TYF Newbie

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    Thanks guys.

    To my knowledge, the fuel pump has not been replaced. When I plug a reader onto it, there are no codes at all. Will get it over to our shop to have it plugged into their reader, and will have them look specifically at the voltage readings.

    When I fill it up, the gauge reads full. The level seems to drop accordingly, but after 50L or so, it's almost in the red. The needle does seem to vibrate a little.

    I definitely want to diagnose before I start buying parts. Not afraid to buy parts, just want to make sure they're the right ones!
     
    liquify33 likes this.
  5. liquify33

    liquify33 Full Access Member

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    FWIW my gauge dances a little but I use the trip odometer as a fuel gauge. I can get 3 days of driving on E and needle goes past F when full.
     

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