UMA tach reading twice the RPMs

I have UMA tach with sender in tach drive on the engine. It is independate of the EFIS and is giving me twice the RPM it should
Tach on screen shows 800, UMA is reading 1600. looked at wiring diagram an don't see any different way to wire it.
Ideas????? Thanks Gary

If you are on P Mags - check the pulse rate in the instructions. It times off the mag.

that might be what I have to do if I cannot find another fix. I DO have the electric pick up on the tach drive on the back of the engine. The paperwork says it gives 4 pulses per revolution, which is twice what I need. The question is:

Is there a way to get the electric pick up on the tach drive to give me ONLY TWO pulses per rotation. There is only one signal wire between the pick up and the tach.

Any thoughts are appreciated

Is there a way to change the settings on the UMA tach from 4 cylinder to 8?
Call UMA and ask their advice.