The Ford Barn

Bobs29ModelA · 12-12-2012, 10:21 PM

OK, this is a strange problem.

My original (cork) fuel gauge float was replaced years ago with a larger brass float (of the type taken out of some other carburetor), and was brazed onto the rod, for a nice solid installation. The gauge was working/reading just fine over the last few years. Then, all of a sudden, the gauge started reading on "0" (Empty), in spite of having a full tank. A check of the float arm up-and-down action showed that there was no binding whatsoever in its movement; however, when you let go of it, it continued to drop down to the bottom of the tank, even though the tank was totally full.

I was thinking, of course, that the brass float had somehow sprung a pinhole leak, and eventually filled-up with gasoline, thereby making the float fail. I then drained all the gas today and removed the gauge mechanism, but, when tested for leaks in a large bucket of water, the float was airtight (as in no bubbles coming out of it), AND, the float was now floating on top of the water just fine! What the heck is going on here, I wondered.

In the meantime, I had already purchased a brand-new fuel gauge unit that came with a barrel-shaped brass float unit, instead of a cork. Before installing the new unit, I tested it in the pan of water, and it, too, had no problem floating at the top of the waterline.

However, once I installed the all-new gauge assembly, now it too stays down on the bottom of the tank, in spite of the tank being full. And, another check for any kind of binding on the newly-installed unit shows no problem.

So, I am at an impasse here... two perfectly good brass-canister floats, and BOTH of them sink to the bottom of the tank? WTH? Is there that much difference in the density or specific gravity of gas versus water, that it'll float on water but not in gas? And (if so), shouldn't this float work just fine, being that it was designed to work as a fuel gauge?

Any help would be greatly appreciated...

12-12-2012, 10:21 PM	#1
Bobs29ModelA Senior Member Join Date: Sep 2011 Location: Livermore, CA Posts: 124	Fuel gauge floats that don't float??? OK, this is a strange problem. My original (cork) fuel gauge float was replaced years ago with a larger brass float (of the type taken out of some other carburetor), and was brazed onto the rod, for a nice solid installation. The gauge was working/reading just fine over the last few years. Then, all of a sudden, the gauge started reading on "0" (Empty), in spite of having a full tank. A check of the float arm up-and-down action showed that there was no binding whatsoever in its movement; however, when you let go of it, it continued to drop down to the bottom of the tank, even though the tank was totally full. I was thinking, of course, that the brass float had somehow sprung a pinhole leak, and eventually filled-up with gasoline, thereby making the float fail. I then drained all the gas today and removed the gauge mechanism, but, when tested for leaks in a large bucket of water, the float was airtight (as in no bubbles coming out of it), AND, the float was now floating on top of the water just fine! What the heck is going on here, I wondered. In the meantime, I had already purchased a brand-new fuel gauge unit that came with a barrel-shaped brass float unit, instead of a cork. Before installing the new unit, I tested it in the pan of water, and it, too, had no problem floating at the top of the waterline. However, once I installed the all-new gauge assembly, now it too stays down on the bottom of the tank, in spite of the tank being full. And, another check for any kind of binding on the newly-installed unit shows no problem. So, I am at an impasse here... two perfectly good brass-canister floats, and BOTH of them sink to the bottom of the tank? WTH? Is there that much difference in the density or specific gravity of gas versus water, that it'll float on water but not in gas? And (if so), shouldn't this float work just fine, being that it was designed to work as a fuel gauge? Any help would be greatly appreciated...