I complained a few weeks back about my fuel gauge not working. I pulled the sender out and discovered that the brass float was full of holes at its ends. The brass ends have disintegrated to a point where all that is left is swiss cheese.I put the sender on an ohmmeter and it appears that the electrical portion of the sender still works. How well, I do not know. I'm getting sick of pouring money into this project. Is there something that I could fill the float with that would make it buoyant and remain so, and be impervious to gasoline? Or, could I possibly coat the float with something like fiberglas and expect it to work okay? Any ideas? It looks like a new replacement part costs about $50, so any cheap fix has to be pretty cheap.

 

Anything will work, it doesn't have to be pretty. Ford used the same cylindrical float for many years, they are under $10 from the usual suspects. I would imagine that would work. I used a cork from a wine bottle for a couple years, eventually it became fuel soaked and sank. The manufacturers used to coat cork with an epoxy resin to prevent this. So a cork coated with a good fuel safe epoxy resin oughtta get ya fixed up real fine for just a couple bucks and a good buzz.

 

You can buy the float by itself. Carpenter has two floats:

$14.95 = The original is made from two pieces of brass soldered together. Solder breaks down, gas seeps in...float settles to the bottom of the tank.

$4.95 = Replacement one piece design.

 

I had a old tank in a boat that had a toilet ball float on it. It lasted over 30 years without a problem. Find out if the spray insulation is gas proof or as suggested use one from a scrap tank.

 

Follow up: I found that I can buy a new float for $5.
So, now my question is what should the ohm readings be from the old sender? I've been online to and I have found conflicting information. For a six volt system, one site says 120 empty &16 full. Another says 150 empty & 30 full. Still another is 140 empty & 14 full. One site sells them by the ohm rating, with a selection of senders available for my '53 truck.
For what it's worth: I attached the sender to the wire from the fuel gauge, grounded the sender body well, and watched the dash fuel gauge respond as I moved the sender's float arm up and down. At the arm's "full" position, my dash gauge only read 3/4 full. So, it looks like I need more than just the float to get things working correctly.

 

Was the arm actually at the top of its travel or just hitting the stop? Before bending the arm to compensate read on:

The original senders and gauges are not linear in response that's why the aftermarket senders don't work properly with original gauges. For example, if the sender reads 10 ohms at full and 100 ohms at empty you would expect that 50 ohms would read half full, right? The original gauges don't work that way but the aftermarket ones do. The original ones might read 10 ohms full and 100 ohms empty (just grabbing numbers for illustration) but half full might be at 32 ohms, or 77 ohms (again, just grabbing numbers) - see what I'm getting at? The wire wrapped around the sending unit card that the swinging point rubs against is evenly spaced on today's units but the spacing on the originals is wound with increasing/decreasing (depending on which way you look at it) spacing between wraps to compensate for the technology employed then. Also, the voltage at the time you tested can have an affect on how it reads, being you have a 6 volt system. Later ('57+) 12v systems actually used 6 volt gauges fed from a voltage regulator that clicked on and off, like a turn signal flasher, that averaged out the voltage to 6 volts. The older 6 volt gauges operated without a voltage regulator and were susceptible to voltage fluctuations - i.e. the higher your voltage, the quicker/higher the gauge will read.

 

The originals don't work on resistance AT ALL. They operate on the King-Seeley design, where heaters move bimetallic arms that have contacts on them. They read the same resistance all the time (the heater coil's), but pulse system voltage at varying frequency to the head unit (dash gauge), which has its own heater/arm.

It appears to be common for gauges on vehicles converted to 12v to read low. Not sure why, because the typical conversion includes a voltage reducer for the gauges. Mine also reads 3/4 tank when actually full. I'm going to bend the arm a bit until it reads more correctly.

 

You got me there, Ross. I forgot about the K-S weirdness, was relying on what's left of my increasingly fractured memory. I recalled the gauge being bi-metallic but had forgotten about the sender also being goofy.

 

Here is a link to a new float. Search Results For: Fuel Float For All Years And Models Parts & Accessories

 

Buy the whole assembly. It would be my luck that I'd replace the float and then the 60+ year old sender would fail.