Power to tach's on yamaha outboards.

[EVERGREEN]

I re-powered my 23 with twin-rebuilt 2-stoke Yamaha 130’s last season and have had no luck getting the tach’s to work. I kept the analog gages from the previous motors because they were in good condition and working fine. My mechanic suggested that it was a ground problem “oil lights not working ether.” I totally rewired the boat this spring with all new harness and grounds. I have trouble shot everything I can think of: Stator, voltage regulator, harnesses, and I am stumped.

The green tachometer wire puts out 5 volts at idle, 5.4 when you accelerate, but will not go any higher. Both motors have the exact same problem!

Anybody have any ideas?