Hydrostatic fuel tank sending unit

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    The last trip I took in the pierce went fine , and I pulled back up to the house and let the engine idle a bit. Then it died, as the result of being out of gas. Instead of guessing how much gas is in the tank, which I am not very good at, or not as good as I thought. I now need to get the Hydroststic unit working or put in a modern float. I have been told that the hydrostatic unit is hard to get to work . And that I should just put in a float type unit. If so what tpye of float should I get. Thanks Doug


    You can purchase a generic float at Advance Auto. I believe this is where I bought a fuel level tank sender model CP7583 Mfg. by Sunpro by Actron Mfg. Co. 9999 Walford Ave. Cleveland OH. They have the gauges to match the unit. I installed the sender unit in my Mitchell gas tank in case I wanted to install a gauge in the future.

    The original units are HARD to get to work and especially HARD to keep working.


    You can buy brand new units, lock,stock, and line if you want to. I admit I just made mine read 2/3 full all the time and kept track of my miles driven to each refill.


    Thanks to you both, Thats what I needed to know. Doug


    Hi Doug,

    I took it as a challenge to get the King-Seeley Hydrostatic gauge to work, because, I also had heard how difficult it is to get it to work. But….it can be done. Time, patience, resourcefulness will be required. I was successful in getting mine to work in my car.

    There have been several good articles in the PASB’s over the years. If you are interested, let me know and I can send you one if you want to read up on these.

    There are several key areas:

    1. The sender unit in the fuel tank, which is a series of brass tubes and cups soldered together must be intact and not clogged up with corrosion flakes, or coated with gas tank sealant coating. Lots of times, vibration or corrosion has caused the sender unit to come apart. If you are lucky, it can be cleaned and resoldered.

    2. You need the fittings and fine copper tubing that is not crimped and the fittings tight with a thin seal of teflon tape at both ends over the threads of the fittings. If you cut the teflon tape to a narrow width, it will not show when the fitting has been tightened. The copper tubing must be routed carefully so that it will not get pinched, kinked, or too close to the hot exhaust system. Never blow through the tubing with compressed air, especially with the tubing hooked up to the gauge or the sender.

    3. The King-Seeley gauge has to be intact, especially the joint between the glass tube and the base of the gauge. There can be NO leaks in the system or it will NOT work. The gauge must be thoroughly cleaned out to remove dust, debris, and residue. Isopropyl alcohol works good with some Q-tips and pipe cleaners for cleaning these out.

    4. Lastly, and ironically, I found that the weakest link of this system is the fluid. First of all, the red color does not stay very long. It tends to fade through pink, and then to clear…making it difficult to read the gauge. It is sensitive to sunlight, which apparently causes decay of the dye. The fluid, much denser than water, is also highly corrosive and if it leaks out, it will chemically attack the face of your gauge and the back of the instrument panel. This is where you have to be sure that the indicator liquid does not leak out through the joint between the glass tube and the metal fitting. Getting the fluid into the glass tube in the fuel gauge without dripping it onto the gauge face takes a steady hand and a lot of patience. A syringe works well here. Getting the right amount of fluid into the gauge is how you “calibrate” the gauge. I found that it was better to slightly overfill the tube, then remove tiny amounts of excess fluid with a toothpick soaking up fluid at the top of the tube. I was actually impressed that once set up correctly, and calibrated with leak-free tubing and a solid sender unit, the King-Seeley gauge works fairly accurately. However, you have to be prepared to change the fluid when it fades, and watch for leaks, especially at the base of the glass tube.

    As Ed indicated above, the King-Seeley sender, the fittings, the copper tubing, and the red fluid are all available, listed in our Parts and Services Directory. If your gauge needs rebuilding, there are parts available for that, too, including several competent people to restore the face of the gauge……(hopefully not after the red fluid has attacked the face of the gauge!) There’s always the trip odometer!

    Getting the K-S Telegage to work properly is an adventure, and you will get a little pride of accomplishment from getting it to work, knowing that this is the way that it was when it left the factory. However, it is not a robust system, and will take some time to maintain and refresh. It is up to you as the owner. As Gene suggested, a float type sending unit, and a matching gauge are much more practical, especially if you are going to do a lot of touring. It is totally up to you what goals that you have for your car. If you want to show your car, know going in that a modern gauge in the dash is an automatic deduction. However, done properly, this is a reversible change and the gauges could be swapped at a later date.

    Happy Motoring,

    Chris Diekman


    Chris, Thanks so much for the great help. The unit sounds like quite a bit of trouble. I think the best thing for me is to put in a float and hide the gauge. And like Ed, just paint the original at a certain level. My main goal is to tour with the car. I have gone to a lot of trouble to restore the car just as it was built by pierce arrow, but I do like to drive and a reliable gas gauge is a must , no one will see it in the open. Doug


    A Packard collector (all of whom are innately sneaky) told me that the red plastic nozzle from a WD-40 sort of sprayer will fit directly in the tube. This installation remains red,and judges very nicely.


    Thanks Tony, I will do that, nothing like a full tank of gas.

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