[Grifter]

I dropped my fuel tank to replace it and bench tested my 47 year old sending unit, it reads 10 ohms empty and 110 ohms full at the pin.

At the resistor where the flat wire connects it read 5 ohms empty and 100 ohms full.

Obviously there is some resistance gained at the pin and resistance goes increasingly off as you move the wiper up to full.

I tried cleaning the contacts around the pin and it seemed to work but a day later the readings are off again. I thought about putting a 10 ohm resistor on the wire but it would still read high at full.

The only thing left is to open the resistor and try to fudge it into reading right but is it worth all the effort?

Or should I replace it now with the tank out and buy a spectra unit for $60?

Thanks

 

[allanjs]

Now's the time to replace it Jeff. Nothing to gain trying to save the old one.

 

[69-Pace]

Jeff - The output just needs to be in the neighborhood of 0 to 90 Ohm's, a bit here or there is corrected by the resistor on the back of the gauge.
5 Ohms is still going to register below empty. 100 Ohm's past full.

But it has served you well and it may continue to work another 47 years or die three seconds after your next fill the tank. You just never know. And to be sure a brand new sending unit could also fail in no time.

If the OEM sender is clean of rust, mechanically sound, the sock is clean and intact there is nothing wrong with putting it back in service. But a new unit bench-tested should give you better peace of mind in the long run. I would then keep the factory unit as an emergency spare.

JMHO

 

[Legeance]

Personally I would keep the original but I would replace it while you have the opportunity.

 

[Jonesy]

Is it single line or dual lines? I would replace it as I think new ones are easily available.
I sent one in to get fixed a month ago for my 74 z/28 because I couldn't find a replacement with 2 lines. Nothing worse than a gas gauge that doesn't work!!