Tach wire

[LewisW96]

I have a '98 200 EFI Mercury and the tach did not work went I got it. I switched the grey wire on the rectifier to the lower one and the tach started working. So does that mean that the upper rectifier is not working? I have had no trouble with the O/B. I have not checked the battery voltage when running. I was thinking that the lower rectifier would keep up with the charging.<br /><br />Also now that I that the tach working, I can see that my WOT RPM is 55-5600. The O/B calls for a max of 5800. Now I got a 14 5/8 X 25in 3 blade. Should I go down an inch of pitch or just leave it? If I go down I think that would put the RPMs just above the max for the engine. I would like to try a 4 blade maybe the same pitch but small diameter. Would that be enough to rise the RPMs to 5800?<br /><br />TIA <br />Lewis

 

[chuckz]

Re: Tach wire

The Tachometer runs off the non-rectified AC signal. You may have been connected to the DC side of the rectifier. <br /><br />Check the battery voltage while running to make sure the charging system is OK. <br /><br />Prop questions I'll leave to someone else.

 

[LewisW96]

Re: Tach wire

The rectifier has a serpate wire that comes out the a potted box(rectifier) for the tach. I still need to check if the rectifier is still charging.<br /><br />Lewis