Hello! New here!
1991 2wd 5speed manual with the 2.3 manufactured 11/90.
Just replaced water pump, thermostat, thermostat housing. Start it and start filling with coolant, waiting for thermostat to open. Idled for 30 mins (in Florida heat) temp gauge never moved off dead cold, thermostat never opened, top radiator hose still empty.
Am I looking at a sensor? Orrr...?
Thanks in advanced!

The sensor has nothing to do with a thermostat opening and closing. The sensor is not near the tstat. If the tstat isn't opening in the Florida heat but the engine isn't overheating, this makes no sense.
Sure are a lot of spam posts lately.

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Not spam.
I guess I left out needed details.
Thermostat doesn't seem to be opening, truck is in fact overheating. Temp gauge reading totally cold, as if the truck is off.
Thermostat is brand new, installed correctly.
Thanks again.

Replace the thermostat again, sometimes aftermarket ones from china are defective. Replace the temp sensor or see if it is even hooked up , plenty of good you tube videos on that.
If the radiator is original, it could be clogged. Turn on the heater and see if any heat is coming out of the vents.
There also could be air in the system but that is hard to have in a pre 2001 Lima 4 banger.

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