BMW K bikes (Bricks)

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1Back to top Go down    Fuel level sender wiring brittle/broken on Wed Sep 27, 2017 7:47 pm


New member
New member
Hi everybody!

I developed a fuel leak from my fuel sender recently, when I pulled it out I found a pretty badly deteriorated O-ring. Bought an O-ring but when I went to put it back in I noticed the wire coatings are pretty brittle. There's a big break in the yellow one, and I put a few more cracks in it myself just monkeying with it. Also, the lead on the other wire is broken. I think someone tugged when they actually meant to unscrew.. But besides that it looks like it's in pretty good condition. I'm really at a loss now because I don't have any electrical knowledge, but I'm pretty sure you experienced gents would advise me not to put it back in the way it is. Thoughts on a course of action?



Life time member
Life time member
Best remedy is to replace the wires. You'll have to use 16GA 19 strand silver wires with PTFE (Teflon) insulation for the longest life repair. Alternatively, you can use 16GA silver wires with PVC insulation, but they will eventually be attacked by the ethanol in gasoline and deteriorate. This type of wire is available at boat supply shops. When I did such a repair, I procured the wire through Ebay from a seller named navships.

You'll need to replace the ring terminals on the ends of the wires during the repair. The positive has a smaller ring terminal hole diameter of 4.5mm; the ground has a larger ring terminal hole diameter of 5.5mm. There are Imperial ring terminals that come close to these Metric measurements.

You'll go through the following process:

1) unsolder the existing wiring from the gas tight connector and the ground lug. Use care. You need a 50W - 80W temp controlled soldering iron to heat the joint enough that the solder melts but the plastic doesn't. Apply the heat and once the solder melts, pull out the existing wire.
2) Clean up excess solder on the lugs so that the hole is revealed. Use solder wick to suck up excess.
3) Cut wires of the correct length and strip 1/8" of insulation from each end.
4) Crimp new ring terminals on the ends of one set of wires. Solder the crimped connector to the wire to ensure a good connection. Use liquid flux to ensure solder flows well. Don't overheat the connection and melt the insulation.
5) Using small heat shring tubing 1/2" long, thread the wire pair through the heat shrink and shrink the tubing over the wires about every 3"
6) Insert the other end of each wire into the holes in the cleaned up lugs. Solder the wire to the lugs, again using flux and just enough heat to complete the job.

Pictures of my last repair:

1987 K75
2011 Moto Guzzi V7 Racer


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New member
Thanks Robert, this is exactly what I needed!


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