Yes, if yours does not have wires, but just a small tube, then it operates with a thermocouple/bourdon type tube. Would be a mechanical type. So that seems to leave only 3 places to go wrong. I have only seen these as a complete unit with gauge,tube and sending unit made together.
1- Engine is really not getting hot enough.
2- Tube is bad, bent or broken inside.
3- Bad gauge.
I just jumped in here because I am in the same process of getting all my gauges to working. Got it down to just fuel gauge left.
