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Thread: Bouncing Fuel Gauge

  1. #1
    Registered User jedwards's Avatar
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    Bouncing Fuel Gauge

    Gentlemen,
    My fuel gauge oscilated backards and forwards as the fuel sloshes about in the tank during driving.
    If the car is stationary, the gauge is rock steady as well. I cleaned the sender with care when reinstalling it, so was wondering if there is a way of supressing its wild swings while driving?
    Logic tells me that irrespective of the quality of the elecrical contacts, the guage will naturall bounce as fuel sloshes around the tank, unless there is some capacitor based supressing circuit to calm its swings?

    Q1. Do I have a fault, or are they all like this?
    Q2. is there a way to improve it?
    Q3. Am i missing some component in my setup?

    regards
    Jeff

  2. #2
    56 & 60 sl & 67 Sedan 230 Andre Hudon's Avatar
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    Re: Bouncing Fuel Gauge

    The float inside the tank is in the middle, not normal to swing.
    I suppose your resistance inside the sender is not touching the needle properly. This is a spring resistance in a semi circular path, which is probably a bit irregular and with vibration, gets off. You have to open the sender and assure the shape of the spring resistance is correct.
    ________________________________
    André Hudon

  3. #3
    Registered User tommd's Avatar
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    Re: Bouncing Fuel Gauge

    Mine moves with the fuel sloshing.
    Tom D.
    1961 190SL

  4. #4
    23K Original Miles slover's Avatar
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    Re: Bouncing Fuel Gauge

    as does mine. But not when the tank is full!
    John Lewenauer - Newsletter Editor - Regional Director
    1961 190 SL
    Click here to EMAIL me

  5. #5
    Administrator wpuryear's Avatar
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    Re: Bouncing Fuel Gauge

    Mine used to with jerky and rapid movement, but like Andre said, the problem was poor contact points. I think sloshing creates a more subdued needle movement.

    Walt

  6. #6
    Registered User tommd's Avatar
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    Re: Bouncing Fuel Gauge

    Walt, maybe there is a difference between jerky and sloshing around. It appears to me that my gauge movement is with the sloshing movement of the fuel in the tank. It does not appear to me to be jerky as if a contact was making and breaking. But I also never thought about it that much. Looked like sloshing, and I accepted it as sloshing.
    Tom D.
    1961 190SL

  7. #7
    Registered User jedwards's Avatar
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    Re: Bouncing Fuel Gauge

    I'm with Tom on this. The movemrnt of my fuel gauge is quite rythmical, as it follows the wave of fuel surging forward and backwards and left and right.
    If my gauge's behaviour was due to poor electrical contact, it would be bouncing between empty (poor contact) and full (good contact). Mine does not do this and I sense that Tom's does not either.

    What I find strange is that Mercedes could not get this right. My 1953 Land Rover Series 1 has a rock steady fuel reading and they do this by having a very long time between sensor movement and gauge movement. The gauge takes about 10 seconds to reach the correct reading on power up.
    My 250SL did not have this bouncing issue and Mercedes were manufacturing W113s at the same time as my 190SL (I have one of the last 100 190SLs built).
    Just seems odd that Mercedes chose not to remedy this rather annoying issue. Or they never did bounce about when new.
    Does anyone have a new sender that bounces?

    regards
    Jeff

  8. #8
    Registered User tommd's Avatar
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    Re: Bouncing Fuel Gauge

    Jeff, from what I have seen, the British often use a thermal type gauge, that heats an element to make it move. The heating makes it move slow. The Germans often used a magnetic coil type that moves quickly and I believe more accurate. I also believe with the 113, they enclosed the sender float in an enclosed tube with a small hole that allowed the fuel to enter and exit the tube slowly to cause the dampening effect.
    Tom D.
    1961 190SL

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