After filling my truck's tank today I found that the gauge still showed Empty. So when I got home I pulled out the seat and removed the sending unit from the top of the tank.
I found that it still works, but the cork float has quit floating. Do I want to coat it with something that's impervious to modern fuel? If so, what is that something? Or do I want to use some other kind of float material? If so, what?
Red-Kote may work for you. If you have some or a friend does. It's about 25 dollars a quart but is great for sealing gas tanks and other items. I've used it to coat a magneto coil with excellent results in sealing the individual wrapped spools and then I coated the entire magneto coil and let it dry. It's now going on two years and still going strong. I've even used it in early rear axle housings to stop oil weeping around the rivets! 10 years experience with that. Hope that helps Steve.
Airplane dope found at hobby stores. I use it on antique outboard cork floats, works excellent.
Fingernail polish or thinned epoxy is what I've heard of using. I used some fingernail polish once on a carb float, but it made it too heavy to accurately regulate the float level. If I had that to do over again, I would try the thinned epoxy. I think it would go on thinner and therefore lighter. On a sending unit, I don't think it is NEARLY so critical that the float be within a 1/64" or 1/32" of where it is supposed to be, so either one would probably be fine. And neither is $25, and you don't have to buy a quart.
Snyder's has a replacement float for the Model A tank gauge made from modern material that survives ethanol: http://www.snydersantiqueauto.com/gauge-float-only
Steve, I sent you an email with a link to a replacement brass float from Summit Racing. It's pretty inexpensive (to my eyes, anyway). It's designed to be clipped into a loop on the end of the float rod, so you would have to re-form the end of your float rod into a loop after you remove the old cork float.
Steve, Go with "Fuel Proof" airplane dope found in Hobby stores. But use it on a new cork (available at most hardware stores. Coat it good 3-4 times, letting it dry in between coats. Drill the rod hole a little oversize and get the stuff in there too. Re-using old corks is just an exercise in frustration. Once they absorb fuel, the cork material starts to break down and they begin gradually shrinking or falling apart. I've tried re-coating old corks and it never goes well.
Fortunately, I'm in the habit of saving packing materials. The thought of Styrofoam occurred to me, so I cut a small piece and set it in a can of gasoline for a couple of hours.
The gas didn't seem to do any damage, so I carved a new Styrofoam float.
It was easy to get it the same size and shape as the cork pieces it replaced.
This afternoon I reinstalled the sending unit in the tank and all is well. I am a happy camper. (The price was perfect.) Now I can get back to T work.