Fuel Sender resistance 1951

Hi, does anyone know off hand what the resistance of the fuel sender would be, empty and full? on a 51 Hornet.

I converted the car to 12v, I never had it running on 6v, so I don't know if the gas gauge ever worked right. I did nothing to the gauges, the original 5 volt instrument voltage regulator seems to work fine on 12v. The temp gauge acts like it should. The gas gauge, however, shows a little over 1/4 tank when the tank is full, and just below the last line at E when it has about half a tank.

I'd like to do a little bit of diagnosing, perhaps substituting a couple resistors of the correct value for E and F, to see if the gauge is working, before pulling the sender out.


  • Geoff
    Geoff Senior Contributor
    10  to 90 ohms.  You may have to do something about the voltage regulator.  
  • squirrel
    squirrel Member
    edited May 2019
    Thanks for the info!

    I tried a solid state 5 volt regulator instead of the original, and the fuel gauge behaved the same as it does with the original regulator. I have a lot of respect for those old thermal voltage regulators...the same design was used on Ford and Chrysler vehicles when they went to 12v back in the mid 50s, they were used well into the 1970s.
  • 40indianssgmailcom
    40indianssgmailcom Senior Contributor
    Would it be correct to assume that this would be the same for a 47 pickup fuel gauge system
  • Geoff
    Geoff Senior Contributor
    No,  '47 used a bi-metal contact fuel sender.
  • So...I finally fixed the problem with the gas gauge. It turns out it was working fine, all the time. The tank really was empty when it said E, and it really had only a little over a quarter tank when it said so. The vent tube was plugged, so I could not fill the tank with more than about 8 gallons. I fixed that, and filled it all the way, and the gauge reads F. Yay.