99 - 90HP 4 stroke TACHO PROBLEMS

[Jeff Gardner]

I have a digital Tach/Trim gauge installed on my boat. Could somebody please tell me how to test the output TACHO signal coming from the motor as the gauge reads 0 RPM all the time

[boats.net]

Check for ac voltage on green wire at tach, as engine rpm's increase voltage should increase.

[Jeff Gardner]

Tested for ac voltage on green wire at gauge as well as on motor after retifier and get nothing. Does this mean the retifier needs to be replaced?

[boats.net]

Check stator to make sure is ok.

[Jeff Gardner]

sorry for the ignorance but is there a way to check output of stator, or are you referring to a physical inspection after removing flywheel

[boats.net]

You would a peak reading volt meter or meter with DVA adapter to test output voltage and an ohm meter to test resistance of stator(lightning coil). Not sure which model you have, in 1999 Yamaha made a F80 and F100 but not a F90 outboard.

[Jeff Gardner]

You are dead right i made a huge mistake with the heading, the motor is in fact a 1999 90Hp 2 stroke - my humble apologies. Do the same tests still apply though?

[boats.net]

On that engine you should get about 11 volts between green and green/white wires at cranking and 25 volts at 1500 rpm's.