Gas gauge calibration unit

Rocky_JS said

I have found when the gauge is outside of that +/- 20 ohm it becomes non functional. Another factor to consider about gauge calibration is the extent of the bi-metal deterioration. The supplied voltage and insulated resistance wire heats up the bi-metal and that is what actually makes the gauge needle move.

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I know what you mean about that. I had a 57 Studebaker pickup. When I first got it, the fuel gauge was lazy. It was thermal too, but had adjustments. I made some tweaks and had it working correctly. I then drove it for another 33 years and the gauge got a tired with age, just like me.

This fix will not fix a gauge that fails to register empty and full with an applied voltage ranging from 0 to 5V. A bad gauge would read above empty with zero voltage, or not able to swing to full with 5V, or fails to be repeatable. With some crude estimates, and Del's tests, I think the OEM gauge reads "Empty" near 1V and "Full" near 3V.

I am in the process of working out the math for the calibration calculations using a spread sheet. I will try post later today.