Tachometer Question

[Searay87]

The Faris tach on my 87 Sea Ray BR17, Mercruiser 3.0 L Alpha One Drive, will at times go to zero while I'm cruising normally in the 3000-3500 RPM range. When I tap the glass cover the needle comes back reasonably close to the previous reading. When I shut down and restart it fixes the problem if I can't get it to read at all.

I'm new to boating but an accurate tachometer reading is something I consider important.

Questions: Is this a problem with the panel display instrument or is it the input?
How does this instrument work?

Any ideas on how to fix this problem would be apprecited.

Note: My alternator went bad today (open circuit windings?). Is it possible there was some electrical arcing going on inside the alternator that may have been interfering with the tach reading? The tach problem has been on and off all season.

Thanks!

 

[Alpheus]

Re: Tachometer Question

If you are tapping on the tach and it comes back. I would say the problem is most likely with the tach itself. Check the wires in the back for loose connections...

 

[fat fanny]

Re: Tachometer Question

The Faria in my Ray does the same thing but does'nt drop dead itwill just intermitently bounce and then calm back down not on any consistant pattern I believe that thier quality is sub par but as for boats it's just one more thing to fix and or replace. and as for your alternator causing this issue it's doubtfull a short,bad connection or coil get a shop tach to verify. Good luck!!!!!!!!!!!!