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Thread: Gas Gauge Fluctuates

  1. #1
    Registered Member Belair-o's Avatar
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    Gas Gauge Fluctuates

    When my car is running, the gas gauge needle fluctuates periodically, moving up to 1/8th of a tank. This happens even when the car is not moving. Any ideas on a fix that might settle down the gauge? I posted this in the modified forum because the gauge is not stock - it is a Westach gauge.
    Thanks, Doug

  2. #2
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    On of mine not sure does something similar, not sure if is my 55 or 56 or both. they have oem gauges.

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    Registered Member BamaNomad's Avatar
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    A small filter across the gauge should prevent fast fluctuations in the voltage to the gauge...

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    might check power, ground and wire connections, too

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    Voltage variation shouldn't affect the gauge output, as a voltage limiter is part of the circuit internal to the gauge. On the other hand, it could be in disrepair.

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    I thought the gas gauges were ammeters, the tank sender being a variable resistor. Thus, a change in voltage would change the current, thus the dial. What am I missing, Rick

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    You aren't missing anything. Voltage is supposed to be constant, resistance of the sender is the desired variable, and the current is what reads on the gauge movement. An undesired variable is voltage, if it changed you would have a false reading. That's why the gauge has the voltage limiter built into it.
    Last edited by Rick_L; 11-30-2021 at 08:52 PM.

  8. #8
    Registered Member Belair-o's Avatar
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    Hi TriFivers,
    Thanks for the replies and discussion. At the end of the day, I don't understand if you think there are some things I should try to fix the gauge fluctuating response. I will look at the connections, as TriFiveRichard suggested.

    If, as Rick says the voltage limiter in the gauge was faulty, could I remotely add a limiter in the sender wiring. Not sure what limiter (or filter?) might be incorporated.

    BTW, I read where sometimes it is suggested to have a ground from the sender to the frame or body, but I assume this is for instances where the gauge doesn't work at all due to no ground. If you think it might help, I will add that ground. Rather than run the ground from sender to frame/body, what if I drilled a hole in the corner of the tank flange and connected there. The sender doesn't leak a drop, and I am reluctant to monkey with it.
    Thanks, Doug

  9. #9
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    If I have learned anything about gas gauges over the years its they need a good clean ground.

  10. #10
    Registered Member Belair-o's Avatar
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    Sorry to be slow and ignorant, but wondered if you had any replies to the questions I asked (please see below). I looked at the connections, and they all look good. I haven't added an additional ground, yet. Don't know if my thought of grounding the tank from the corner of the tank is dumb (reasons stated below). I don't know if I can put a voltage limiter in the circuit in a remote location (like near the tank), to test the concept. I don't know what an appropriate voltage limiter would be.
    Thanks for your consideration. Doug
    Quote Originally Posted by Belair-o View Post
    Hi TriFivers,
    Thanks for the replies and discussion. At the end of the day, I don't understand if you think there are some things I should try to fix the gauge fluctuating response. I will look at the connections, as TriFiveRichard suggested.

    If, as Rick says the voltage limiter in the gauge was faulty, could I remotely add a limiter in the sender wiring. Not sure what limiter (or filter?) might be incorporated.

    BTW, I read where sometimes it is suggested to have a ground from the sender to the frame or body, but I assume this is for instances where the gauge doesn't work at all due to no ground. If you think it might help, I will add that ground. Rather than run the ground from sender to frame/body, what if I drilled a hole in the corner of the tank flange and connected there. The sender doesn't leak a drop, and I am reluctant to monkey with it.
    Thanks, Doug

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