Temperature gauge jumps to HOT when I turn the key (prior to turning over)

hi all! When I go to turn the key and prime the fuel pump, my temperature gauge skyrockets to HOT, and then when I turn over the engine it stays in the HOT range even though I know my coolant is flowing fine.

Previously (using the same intake/carbs/temp gauge/thermostat) my gauge wouldn’t rise upon turning the key, and my engine typically ran on the cooler side!

This happens both with the temp gauge wire connected to the thermostat AND disconnected (checking for bad ground or something)

Anyone seen this before?

Stage One Rover 3.5L V8 on twin Zenith
Strombergs

Guessing the wire is rubbed thru somewhere and touching ground

As above, try a new wire direct from gauge to sender if you can not find issue.