Tach Question

[newbassboat]

I have a 1984 90hp Johnson. I am having Tach problems I have read all of the fixes for Tach issues, but still have a question. My tach did not work so I got out the meter and checked it out according to what you fellows have suggested. I have 3 wires going to the Rectifier. Solid Yellow, yellow / Grey, and Red. I have 12v going to the red when ignition is turned on nothing on the other two. When I start the motor and at Idle I have 4v on the Solid yellow and half a volt on the yellow/grey. If I connect the grey tach wire to the solid yellow the tach works. It was connected to the Yellow/grey and did not work. Will it hurt to leave it connected to the solid yellow? I am figuring that I have a faulty rectifier. I also would like to know what RPM's I should see at WOT. This motor is on a 1990 17ft Alumacraft.

 

[newbassboat]

Re: Tach Question

I would also like to add that when hooked up to the solid yellow wire I had approx. 1000rpms at idle.

 

[Barnacle_Bill]

Re: Tach Question

Check to be sure your system is charging. It sounds like one side of your rectifier has a shorted diode. The tack should work on either of the 2 yellow wires coming from the stator.

 

[newbassboat]

Re: Tach Question

Ok Thanks for the Info. I have checked and I had about 13 volts at the battery when the motor was at Idle, But I will replace the rectifier anyway. Can you tell me what rpms I should have at WOT?

 

[ob]

Re: Tach Question

5500 - 5800 rpms at wot with an average load aboard.

 

[newbassboat]

Re: Tach Question

Ok thanks alot ob!!