Only thing that has changed is that I got rid of my dizzy and coil since going with Megasquirt. Voltmeter on the sensor wires gives an erratic volt reading. I tried looking at the schematic and it's not making sense. Maybe gauge when tits up, but the timing of this issue makes me think it's something I did.

Any clues?

First thing I'de check is the integrity of the wire crimp on the bullet connector that goes on the temp sensor. Pull back the outer clear (well, used to be clear... now yellowed) boot and have a good look and maybe replace the connector. The wire strands get corrosion buildup inside and maybe only a couple of strands are barely hanging on. Same for the starter trigger connector.

I have a newer sensor that has a screw to clamp down an eyelet wire end. All is tight. So I can wire up an aftermarket ECU, but can't figure the temp sensor-I guess I need to get chasing wires.

Gauge now works - I don't know why -sorry guys

Fm???

Gauge now works

My temp sender was intermittent. Would occasionally alternate between normal and open circuit. Some days, it would be fine, and other days it would be flaky. Replaced the sender and problem went away.