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Thread: Mysterious fuel gauge level indication….. anyone run into this?

  1. #1
    Senior Member Haasman's Avatar
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    Mysterious fuel gauge level indication….. anyone run into this?

    Mysterious fuel gauge level indication…..


    On the ’73 car the fuel gauge had been stuck on 1/3. I thought it was a bad sending unit so I replaced with a new one. Same problem. I then took both the gauge and the sending unit to Palo Alto Speedo. They said it was now working fine.

    Before I re-installed the gauge and the sending unit, I connected the sending unit and watched the gauge move as I tilted it back and forth. OK it works.

    After installing I began to notice the gauge was once again stuck at 1/3. Does this ring a bell with anyone? Has anyone experienced this? I thought maybe a bad ground or connector, but all seems fine.

    What should I go after/look at?
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  2. #2
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    I’ve seen this happen when the tank has a bump in the bottom. Or if the sender mounting location is tweaked or bent.

    Basically the sender tube is binding.
    looking for 1972 911t motor XR584, S/N 6121622

  3. #3
    Senior Member Haasman's Avatar
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    Interesting, thanks for the reply. I did move the float back and forth before installing it into he tank. Hmmmm someone else asked me if I had gently torqued the little 6mm bolts that hold the sending unit in. The idea being that an uneven tension on the sending unit flange might be flexing it and causing distortion and binding. Have to admit that seems a bit out there as the little bolts hardly have any torque on them.
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  4. #4
    Do you have a stock tank?
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.

  5. #5
    Senior Member 30westrob's Avatar
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    Very interested in your solution, as I have the same problem I have been chasing for years. Thinking about putting several gaskets under the sender to see if the float is binding. What does not make sense is my gauge will not go below 3/8 when the sender is installed, but if I keep driving the low fuel light comes on indicating the float is at the bottom of the sender. Rob

  6. #6
    Senior Member Haasman's Avatar
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    Ed- yes stock tank

    Rob- Glad your low fuel light comes on, with mine the needle now just hardly moves. Fill it or run it low, it still now hovers around that 3/8 level.

    The sending unit has a cork gasket, btw. I am wondering if it is a bad ground?
    Last edited by Haasman; 04-05-2021 at 06:59 AM.
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  7. #7
    Senior Member Haasman's Avatar
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    .... and to add to the drama .... the 914-6 has the same problem. Just noticed this weekend when fueling it up. Do I have 2 bent sending units?
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  8. #8
    member #1515
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    After 48 years of ownership, I think I can safely say that the fuel level gauge is not very accurate. I use the trip meter to give me a better indication of how much fuel I have left, at 200 miles I know it is time to refuel.
    David

    '73 S Targa #0830 2.7 MFI rebuilt to RS specs

  9. #9
    Member cairo94507's Avatar
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    Huh....my '71 914-6 just developed this problem too after a full restoration and 3K miles of driving. My gauge stuck at about 1/2 tank for 2 days and then began working for a day and now is stuck at 1/3 tank. I was ready to order a new sender from Gaudin Porsche to see if that resolves this issue. I will likely still do that and very careful install it and gently tighten it into place.

  10. #10
    Senior Member Haasman's Avatar
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    Cairoxxxx please let us know how it goes. Interesting how this is more of a common problem than first believed.
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

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