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  1. #1
    FEP Power Member fgross2006's Avatar
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    Default Fuel gauge calibration

    Not sure why this happened but my fuel gauge is way off calibration. I had the cluster out a few times last summer so something jostled it.

    on empty it reads at 1/2 full. I learned the hard way by running out of gas. At full and topped off the needle is buried so far to the right that it cant be seen on the face of the cluster.

    The guy in Texas that retro-fit my amp gauge to a volt gauge can calibrate it for $15 but it could be 4 to 5 weeks to get it back so I'd rather fix it myself.

    Any suggestions on getting the gauge to read correct?

  2. #2
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    Default

    My 84 svo did the same thing to me but it rarely gets driven. I just replaced the in tank sending. The circuit is pretty simple and works on about 10 to 70 ohms range.

    Possibilities:
    -IVR drifting, pulsing 5.0 volts
    -Sending unit float or resistance issue, 8 to 86 ohms. On or above full at 73 ohms.
    -Gauge, ohm out the gauge. Upward needle movement for 10 to 15 ohms is normal. Less than 10 or over 15 is a bad gauge per the service manual.

    FYI, the low fuel warning system is a separate system tapping off the fuel sensor input signal. It should work independent of the gauge and come on at 1/4 tank.
    Last edited by KevinK; 04-30-2024 at 01:28 PM.
    Fox Body/3rd Gen MCA Gold Card Judge
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  3. #3
    FEP Power Member fgross2006's Avatar
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    Default

    Quote Originally Posted by KevinK View Post
    My 84 svo did the same thing to me but it rarely gets driven. I just replaced the in tank sending. The circuit is pretty simple and works on 10 to 70 ohms range.
    -IVR drifting
    -Sending unit float or resistance issue
    -Gauge
    I replaced my in tank sending unit already. Its the gauge that's off. When the car is off and the battery disconnected it reads 1/2 tank.

  4. #4
    FEP Power Member 4-barrel Mike's Avatar
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    Default

    Pull the gauge and push the needle to "E"??

    Mike

  5. #5

    Default

    I have this exact same problem in 20th Anniversary convertible. The sending unit was replaced a few years ago and it was confirmed to be the correct sending unit for the car before install. I know there is more than one sending unit and it was made sure to be the right one.

    Could this be the anti slosh module? Sounds like I may also need to do an Ohm measurement on the sender.
    Last edited by tjm73; 05-21-2024 at 10:01 PM.

  6. #6
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    Default

    The difference in sending units is fuel injected or carb. All sending units 86 and earlier work on the same ohm range. Anti slosh module started in 87.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Turbo Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 07 GT500,
    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

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