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Thread: How do I fix inaccurate fuel gauge?

  1. #1
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    How do I fix inaccurate fuel gauge?

    Back in 2010, I had a friend install a Racetronix fuel pump kit for the LS3 motor in my '98 Z28. On the immediate test drive following the install, I notice the fuel gauge reads empty and I barely manage to get to a gas station, but it only took like 10 gallons to fillup. So we figure the sender arm was some how bent during installation. Since it was such a big PITA to drop the tank, I put it off. When I found out there were very few stock sending arms left in the nation, I ordered one and it sat in storage another 3 years until a few weeks ago when I took it to the dealer to fix the fuel gauge.

    However, they wrote the ticket up as 'replace fuel sender, customers part' and not a diagnostic, so they don't apear to be willing to warranty anything after I paid $500 in labor. The Tech 2 is reporting 12.6g remaining on a 15.5g capacity when the tank is full. I rarely let it get below an 1/8th tank because I don't want to risk being stranded. Factory behavior was below E when truly empty and above F when truly full.

    Would there be a workaround process to recalibrate the factory fuel gauge back to stock behavior? If yes, can someone please provide the detailed steps? Thanks!
    Last edited by JimMueller; 05-17-2014 at 10:05 AM.
    1998 NBM Camaro Z28
    LS3 motor
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  2. #2
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    No ideas on how to adjust the PCM tables to to fix the gauge?
    1998 NBM Camaro Z28
    LS3 motor
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  3. #3
    When I installed a new fuel sender in my 57 I had to calibrate it to the tank size. The only way in your case I can see changing the calibration would be to read the resistance on the gauge at empty, half, and full, then interpolate the values in between. What PCM are you running?

  4. #4
    Senior Tuner mbray01's Avatar
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    Well, the dealer would only be responsible for the labor warranty, was something they did while installing negligible? you brought your own part, you diagnosed the vehicle, and simply asked them to install a part. IF that diagnosis was wrong, the dealer is responsible for nothing, point blank regardless of how much you spent.

    now for your concern, you have to go into fuel system, and there are tables for adjusting the fuel level sensor, you will have to take a measurement completely empty, to completely full, and interpolate the values
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
    Advanced Level Specialist
    Custom Car Fabrication, Customization, High Performance.
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  5. #5
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    Well, I screwed up and signed the repair order without noticing how the work order was phrased. What I wanted was for them to diagnose the inaccurate gauge, and provided a new fuel sender if it was determined that was the problem. They're going to cover the diagnosis for free whenever I can get the vehicle back in.

    I have '98 F-body OS 9375576. The Fuel system tables I have and the existing settings are:

    Capacity: 15.51
    Sender Max: 150
    Sender Min: 20
    Fuel Gauge Output vs Level table: 116.85 to -200 PWM
    Fuel Primary Volume vs Level: 0 to 15.85, unknown units
    Secondary Volume vs Level : unused, all zeros

    I found the thread below, maybe that'll have enough information for me.
    http://www.hptuners.com/forum/showth...429-Fuel-Level
    1998 NBM Camaro Z28
    LS3 motor
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  6. #6
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    I have a 95 TA installed the 24x and LS1 PCM, a 255 lb pump and know mine reads way high and drops like a led balloon. I have adjusted every setting there is and none seem to make a difference. Mine is driving me crazy.