not enough info - which model Faria tach ? also Faria are sub par quality from their mid level and down entry level gauges as they seem never to last and some not even lasting a year.

Have no idea which faria model ---- is it a faria smartcraft tach or analog with digital hour meter built in or just analog tach ? then which model --- Also all Faria gauges can be sent back for testing - they are located in PA - and most all have a life time warranty. There will be a small fee for doing this route.

************* Important info here *********** Next huge question would be -- does your engine start and run ???? if not and no tach signal YOU HAVE A BAD CRANK POSITION SENSOR.

Theres a converter from analog to digital for the 496 swap, look around on OSO using the search function. Theres some info on it, good luck.

Quite often, the "bargain" marine tachs get oxidation on the selector switch contacts. If the boat lives in saltwater, even moreso.
Assuming you have no problems with your wiring and the tach previously operated okay and then STOPPED working, then you can try to spin the selector back and forth a dozen times or so to mechanically clean the contacts. If it starts working, then you can shoot WD40 into the weep hole to try to get a film of protectant on the switch contacts to prevent it from happening again.
If this is a NEW tach installation that you can't get to work, then its a different story and you'll have to diagnose your installation.


MC