Tach gone crazy

SilvrTour wrote:2006 Sabre, Merc Opti 115 3 cyl. Tach is reading 4000 rpms at idle, bounces all over the scale and winds way past the 8000 rpms level at speed. Bad connection, bad tach, …??Tachs are made for different Mercury motors. (3 cylinder, 4 cylinder, 6 cylinder etc.) There is a little switch on the rear of your tach that is set for your motor. Take a small flat blade screwdriver (note the position that the switch is in now)and just rotate the switch back and forth many times and put it back where it was before you did that. This should clean the contacts of the switch and take care of your problem. Let us know if this solved your issue.Everyone should believe in something. I believe Ill just go fishing!

Bass Cat Boats wrote:That is actually the pulse reading on the signal from the stator. It is not the cylinder number. WE think you either have a voltage regulator issue or a bad tach. BCBThanks for the info BCB. I didnt realize that. I had the same symptoms on my tach once. On the recommendation of our local Mercury Mechanic, I simply worked this switch back and forth several times and that problem went away. Its at least a “first thing to try” in this case.Everyone should believe in something. I believe Ill just go fishing!