1936 fuel sending unit ohms

Working on my own 1941 sender now. 99% certain it's the original K-S sender. The gauge was stuck indicating full. Very low resistance (single digit ohms) between the sender and ground. That's consistent with stuck full.

When I pulled the sender out of the tank the float arm was stuck full. The float is fine (but rusty) and would not 'fall' to empty on it's own but moves ok by hand. 'Worked' it a few times my hand and it seemed to loosen up and fall on it's own but then all the gasoline dried up and won't move anymore except by hand.

Now the gauge is stuck on empty even when moving the float all the way up and all the way down by hand. Resistance is now stuck at around 40 ohm. Sounds like the contacts need to be cleaned.

Any thoughts on lubricating the float pivot arm without contaminating the gas?


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I have been told by other Ford barners that if you remove the top of tha gague you can clean the points.
I have a 12v system. I am having my own problems. I have replaced the KS sender with a Bob Drake sender that they say works with a 12 & 6v system. Still the gague goes up and out of sight past full.
 
SoCalCoupe said:
Working on my own 1941 sender now. 99% certain it's the original K-S sender. The gauge was stuck indicating full. Very low resistance (single digit ohms) between the sender and ground. That's consistent with stuck full.

When I pulled the sender out of the tank the float arm was stuck full. The float is fine (but rusty) and would not 'fall' to empty on it's own but moves ok by hand. 'Worked' it a few times my hand and it seemed to loosen up and fall on it's own but then all the gasoline dried up and won't move anymore except by hand.

Now the gauge is stuck on empty even when moving the float all the way up and all the way down by hand. Resistance is now stuck at around 40 ohm. Sounds like the contacts need to be cleaned.

Any thoughts on lubricating the float pivot arm without contaminating the gas?
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Moved the float arm by hand several cycles and decided it would work ok. The reason it was still stuck on full is I forgot to ground the sender while testing.


The gasket was probably the original 1941 gasket so I make a new one out of Felpro gasket material.


This did not go well at all. I filled the tank just before going home from a cars and coffee and checked on the car an hour later in the garage like I always do. GAS EVERYWHERE! The fill pipe was full, the level higher than the sending unit and gas was leaking out of that joint. I'm 90% certain it was coming out the six screw holes. The holes seem to go all the way through into the tank and weren't sealing. I don't think I stripped the screws but it's so easy to do with old worn screws and holes; you don't get the same snugging down feeling the way you do with new screws.


Stopped the leaking by siphoning gas out of the tank but I'm really stumped about permanently stopping the leak around the sending unit. New gasket? RTV sealant? Helicoils for the machine screws?
 
The original gaskets were cork. An alternate would be neoprene rubber.

The screws and threaded bores need to be checked for condition. They have to be functional to seal. There are heli-coils for all sizes of screw threads so that may be an alternative but even the helicoil would need to be sealed.

I use Flame Master Chem Seal tank sealer when I run into a problems with fuel sealing. I purchase the CS3204 B1/2 which has a good work time (1/2-hour) and cure time is basically overnight. I purchase the small can since I use the stuff to seal other things as well. It dries into a rubber like material when fully cured. A person can use it on the gasket but it will make it difficult to remove later. I use a razor blade and work it into the gasket flange if I have to do that. The screws can be sealed with it as well. The stuff ain't cheap. here is a link. Sem kits are cheaper but they are a one time deal since the whole kit will cure after it is mixed.
https://www.aircraftspruce.com/catalog/appages/chemseal09-04612.php

I also use other brands like Products Research PR1422 and Pro Seal PS890 if I can't get the chem seal.
 
I once made some small annealed copper washers to go under the sender screwheads to stop a leak I had. I also used extra wide truss headed screws.
 
BTW, the sending unit electricals work fine. I neglected to ground it the first time I tested it. When it's grounded and I move the float lever by hand, it works fine.



C&G Ford parts has a $10 shipping fee. Not complaining. It's pretty reasonable but I was a little hesitant to order a $3 gasket + $10 for shipping. Not that I haven't done that before. Actually, they're only 35 miles away, 42 minutes from my house, but I'll pay $10 to avoid that. Scrounged around and found another part to buy to make it worth the $10 shipping and ordered a new gasket.


It's a nice cork gasket. The screws weren't stripped. Fiddled around with the screw holes quite a bit to clean them up and installed the new cork gasket. Filled up the filler pipe above the level of the sender with a gas can. No leaks.


Now the gas gauge doesn't work. 95% certain it's just the arm that's stuck again; very likely on the original rubber bushing



One step forward, one step back.


Any recommendations for a sending unit rebuilder? To all appearances it's an original King-Seeley sender. I'd really like to keep it just because it's original. No doubt I could sneak through even a very tough judging with a newer replacement. The car won't be judged anyway, but that's not the point for me, just the satisfaction of restoring the re-war technology and getting it to work.


As far as fixing the original goes, this is one of those cases where experience really counts. Having the right tools and right knowledge makes all the difference. It's pretty delicate and I can see myself wrecking it.
 
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