My sender stopped working and when I took it apart I found the resistance wire had snapped (this may or may not have been as a consequence of something stupid I did ).

I searched here first and couldn't find anything, so figured I'd post this fix in case anyone has the same problem in the future. As much as I'd like to take credit, it was largely informed by this post on The Samba

The wire in the sender is nichrome, a high-resistance wire. 12 inches of the broken wire from the sender read approx. 42-43ohm on my multimeter.

So, all you'll need is:
1. Soldering Iron
2. Solder
3. 42.2 ohm, 38 gauge nichrome wire for $3 from Jacobs Online


Step 1:
Use your soldering iron to heat and remove the solder attaching the ends of the snapped nichrome wire to the sender. Once you've removed the remaining pieces of wire, keep going until you've also removed all the old solder - underneath you'll find a hole in each of the tabs to thread the new wire through.

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Step 2:
The nichrome wire comes on a cardboard spool. Remove enough of it to go from one tab down to the bottom of the sender and back up again + about 5 inches. Pull it through your fingers a couple of times to straighten out any kinks - it doesn't have to be perfectly flat.

Click to view attachment


Step 3:
Thread one end through the hole in one of the tabs you removed the old wire from. Pull an inch or so back on itself and then hold taut as you solder it in place.

Click to view attachment


Step 4:
Thread the wire through the metal contacts on the side of the float...

Click to view attachment


Step 5:
... and then down and around the black plastic piece at the bottom of the sender ensuring it doesn't touch the metal post (as in pic).

Click to view attachment


Step 6:
Now, going back up toward the top of the sender, thread it through the metal contacts on the other side of the float (so same as Step 4)...


Step 7:
... and through the hole in the opposite tab, again pulling back on itself to ensure it's taut, and then solder in place.


Once it's cooled you can cut off the extra pieces of nichrome wire either side of the solder on the tabs and reassemble the sender.

Then simply test your solders are good by either reconnecting it to the gauge and inverting the sender while still out of the tank to check the needle moves or, if you have a multimeter, connecting it to the two left pins (diagram below) on the top of the sender and watching the ohms increase/decrease as you slide the float up and down.

Click to view attachment


One final thing, when soldering be careful not to accidentally touch/burn the copper wire that runs the length of the sender and grounds the warning light... If you do, a simple fix is to strip the insulation off a piece of electrical wire, remove the copper wire from inside and solder one strand of it in place of the broken copper wire.



John

Good job on this.
Thanks for the write up.

With new fuel sender costing about $160 that is good to know. I might have a couple that could be repaired.
Bruce

Bruce, I'm guessing you have the ability to do this yourself, but if not I now have about 9.6 meters of nichrome wire that will more than likely be gathering dust forever and would be more than happy to do it for you if you wanted to mail them over.

John

This has now also got me wondering if you couldn't match a non-stock gauge to the stock sender by using higher or lower resistant nichrome? Although that could be straying into DAPO From Hell territory...

From the pin out picture, which one goes to ground? I don’t have a electrical fitting to show me. Aaaa

My fuel gauge pointer bounces and sticks pretty regularly. What is the fix for this? Just remove it and clean the wires or...?

The nichrome wire is great for a heating element if you want to cut Styrofoam. I was looking for some a few months ago and just bought a ready made cutter for my girls school project.

Thanks for the write up.

That is what it looks looks like! Remove, clean test install.