Electrical Tachometer issue

I’d pull the tach out and bench test it.

You can use this procedure to see if it’s a tach issue, or an issue with the wiring from the coil.

This is a tach calibration vid, but you can use that same $10 Amazon signal generator to command certain rpm signals and see if the tach responds correctly. Then you can determine if you need to get a new tachometer, or investigate the wiring/tach signal.

View: https://youtu.be/UkHoSIdTpbc