tach not working

[mtnman05]

My tachometer isn't working in my 1994 Ranger bass boat. I am assuming it is an issue at the motor. The motor is a 175hp Mercury XRI. I have checked all the wires at the tach and they are connected. Also when I turn the ignition switch on the needle on the tach moves up about a 1/16th of an inch to point directly at 0, but when I crank the motor the needle stays at zero.
Where should I start looking? What does the tach read off of?

 

[reddogg]

Re: tach not working

There are 2 windings on the stator, one is for the tach. I'm a johnyrude guy so cant say which one on your motor, but you might want to look into it.

Red

 

[CharlieB]

Re: tach not working

The tach is driven by the grey wire on the voltage regulator/rectifier. A failing tach is often a sign of a dead charging system.

Check battery voltage withi the motor OFF, then again running at about 2000 to see if voltage rises.

If your motor has twin rectifiers, disconnect one while you test the other, plug the grey tach lead into the other.

If it is NOT charging you need to further test both the rectifier and the stator to determine which is at fault.

Repost your progress.