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37 gauges were magnetic so some movement of the needle is normal when it first gets power before things become stable. The gauge must also be grounded to work properly.

The always on or potential coil is weaker, goes active and will want to pull the needle one direction. The series coil connected to the sender, being slightly stronger, will overpower it and want to pull the needle to the other side. The changing difference will make the needle track as the sender changes the coil strength.

No idea on the resistance range for that gauge and sender but the old and now obsolete range of 100 empty and 0 full was used on S-W magnetic gauges in Clippers. KM Lifestyes has recently made new senders for other 37 owners if you find you need one.

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Howard,

Thanks for that. I'll recheck to verify what I am seeing but based on the test procedure. It appears it is always pointing to empty. Now that being said, I don't see any marking on the terminals on the back of the gauge, so does it matter which terminal is connected to tank wire?

In this application, I am running 12v negative ground, but I am using a 6v Runtz converter on the power side.

I'm just bench-testing this at the moment and have the cluster grounded as the runtz requires a ground as well.

It does matter which terminal connects to the battery as one terminal will power both coils and the other will only provide a sender ground to its coil. I would start by seeing if the gauge terminal layout is anything like the illustration. That drawing is out of the 37-8 SM and Packard usually had components drawn showing terminals in their approximate locations. In this case I would try the battery on the terminal in the middle and the sender to the one at the top. If that does not work then it would be a matter of trying to ohm the coils or if you can see inside the gauge, maybe the wires are visible.

I'll take a look again. But I think the terminals are oriented horizontally vs vertically on this 115-C (JR) gauge.

But I recheck everything when I go back out there this evening.

You might look very carefully at the insulator paper and see if some indication is stamped on the paper itself. This is a 41 horizontal layout gauge (different brand) and you can barely see a faded stamp or imprint next to the terminal.

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Howard, thanks, I will check that. The paper between the terminals is ripped away, but the base paper remains.

Hard to read in that photo, does that say IGN? (Ignition).

I think so but my eyes are not great anymore.

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Unless my eyes are deceiving me, I believe this says "TANK".

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