[bigeasy1]

I'm not sure what feeds it,and unfortunately I can't get back up to the boat for a couple of weeks.
Hope to get up there and install my new(to me)radar unit in the next few weeks,and plan to give the tach problem a going over at that time.

Quite a few people have told me to move the selector switch on the back of the tach back and forth several times.They claim it's common to get corrosion on the internal contacts at this switch point which causes erratic readings.
I only hope it's that simple.I'll llet you know what I find.