Repair fuel sender?

[Indianajohn 53]

The fuel gauge on my new (to me) 520H isn't working. The gauge is getting power and ground. If I ground the brown wire at the sending unit, I get FSD on the gauge needle, so I know the gauge itself is okay. I pulled the sending unit and get nothing from the white wire to ground no matter where the float is positioned (infinite ohms). If I test from where the white wire is soldered on over to where the bare wire wraps around to the first winding of the rheostat, I get continuity. But if I go from the white wire to the actual first wrap on the rheostat, I get nothing again. So it appears that the bare wire is broken between the where the white wire is soldered on and the first wrap on the rheostat. Of course it is on the back side where I can't get to it. Has anyone ever taken one of these apart and successfully repaired it? It appears that you would have to drill out the brass rivets that hold the restart part to the metal brackets, solder the broken wire, and replace the rivets with small bolts or something similar. I figure I have nothing to lose by trying. It's not working now anyway. My guess is that these are very expensive to replace. None on eBay right now. Any thoughts, encouragement, or otherwise?

Thanks!

[tbarnhart 240]

Have at it. Your approach sounds like it would work, although that tiny wire they make those senders out of is a pain to repair. Like you said, you don't have much to lose. At our shop, we call it the "rotten egg theory", as in, "you can't ruin a rotten egg". If it's already no good, can't really make it much worse.

[woodchuckfarmer 333]

Member Wheel bearing did a rebuild on a 520 and I think he used one from a car . Not real sure,  but its worth looking for.

[Indianajohn 53]

Thought I would finally post an update on this project. I was able to get the sending unit apart and repair the broken rheostat wire inside by soldering. Wasn't easy, but it does work after a fashion now. Since I ended up having to shorten the wire by a couple of turns before soldering it, the gauge won't go full scale anymore. But at least it does work well enough to satisfy me. I'm more interested in knowing when I'm about to run out of gas than when the tank is full. I was able to carefully grind the heads off the rivets to separate the housing and get to the rheostat to repair it. I then used very short 10-32 screws and nuts to reassemble it. So I would call the repair a qualified success. As usual, YMMV.

[evanloock 221]

Since the earlier 520-H and 520-HC models used gauges (including the fuel gauge) sourced from Stewart-Warner, I bet the fuel gauge sending unit was as well.  I have seen on their website that they have a myriad of sending units available.  I bet one might just be correct for the 520 tank.

Edited April 16, 2017 by evanloock