Coolant Temperature Sending Unit Question

If the coolant temperature sending unit is bad...will the temp. gauge move at all? My gauge moves to about 1/4 warm and the car is obviously overheated. 94 Z24 3.1L

Chances are your coolant is not flowing properly. Flush everything, check for leaks and possibly replace your coolant pump.

the coolant was boiling...doesn't that mean it was flowing through the hot engine, but not getting cooled?