View Full Version : Fuel Tank Sender

Nemo von Klepper
06-28-2019, 04:24 PM
I have my tank off, giving it a clean up. It looks better on the inside than the out which makes me think the previous owner bought a new one from “Tankauto” just before giving up on the refurbishment 20 years ago (?)—tags are from ‘98. I was going to Red Kote it, as per recommendations here.

I don’t know if they even bothered to hook up the fuel tank sender. Anyway, I don’t know if it would have worked if they had. I’m thinking it and the carb might be some of the few original things left from the original fuel system. Did the originals have cork floats?

06-29-2019, 08:11 AM
[QUOTE=Nemo von Klepper;8427] Did the originals have cork floats?

Well, Mr. Google has a nice picture of what looks to be a CJ 3A sender (five holes) with two corks for a float. I'd have to say "Could have been ...".

I'd check the unit out with an ohm meter before you reinstall it. A rough guess is about 25 ohms with the float at Empty and just a couple of ohms at Full. (But, some places say 240 ohms empty and 35 ohms full, so I can't really say about a CJ 3A). In any case, if there are skips or jumps as you move the float up and down, those are corroded places on the resistance wire or the slider. Not good - I'd consider a replacement.

There are all sorts or horror stories about replacement fuel gauges that don't work, so if you replace one end of the set - it might be a good idea to replace both ends. 12-volt conversions seem to have the most issues unless you keep the old gauges and add a 6-volt post regulator for the gauges. They are very simple three wire devices, cheap and they take a lot of hair pulling out of the instrument conversion. Does the CJ 3A have mechanical oil and temp gauges?

My next major project on the '48 is to calibrate the fuel gauge/sender. I will get the neighbor kid (teen age muscle) to help me and I will do it with the tank off the truck, using water vs. gas to do the calibration. I know I will need to do some bending on the float arm and maybe add at least one, maybe two, resistors to set Empty and Full - a real science project. Three of the four gauges are reading "correctly" now and I just need to get the fuel gauge settled down.