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Fuel Sending Unit Wire Solder

3K views 5 replies 6 participants last post by  wilderbry 
#1 ·
Does anyone know how to re-solder the resistor wire on the gas sending unit to the through wall sender plate?
It doesn’t take solder. Is it welded or titanium or something?



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#3 ·
Soldering the sending unit wires to the brass rings takes a bit of cleaning, good flux, proper solder and heat. I have re-wired several tank sending units with new NiChrome resistor wire, and also repaired several by soldering the ground ring to the sending unit body.
 

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#4 ·
I think you hit the nail on the head. Nichrome wire has a chrome oxide surface that is very different than copper or steel. The surface is not easily reduced to the unoxided, metal state. You should be able to 'tin' the surface with a good electronics grade silver solder, the appropriate flux and higher heat. Once the surface is 'tinned' it should be possible to get electrical solder to adhere.

Someone else mentioned microscopic spot welding. There is a common industry method using a micro spot welder to attach wire to nichrome, tungsten and other metals, but it is unlikely you will find this in a welding shop, but maybe a high end instrumentation and electronics shop.

Used a similar method to make thermocouple tips from dissimilar metal wires for decades.
 
#5 ·
Only a "metallic clean" surface will accept the solder to stick on it. If it is oxidized or has a (very thin) coating on it, the solder will not stick. The best flux and the highest heat will not burn it off. You will have to use a tiny file and clean off whatever is on the outside of the wire, then solder it like any other clean wire.

Dieter
 
#6 ·
I have soldered new nichrome wire many times, a good tip to clean up the places to solder is to use Tarnex or similar acid cleaners to remove any oxidation. I am using a regular pencil solder iron, and electric wire solder both from Menards and never had any problems. Be sure to clean the float contacts as well. You can get the repair "kit" or wire from OGTS.
 
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