Tachometer not working correctly

[RAM1961]

I bought a 2012 24′ Bentley SE with a 115 Mercury about two months ago. Took it out Saturday for the first time (too much snow and ice two months ago) and wasn’t 100 yards off the dock when I noticed when I had it in forward gear, without applying any throttle, the RPM meter was showing around 2100 RPM’s. That didn’t sound right and after a bit I opened up the throttle not quite halfway and the RPM needle actually pegged way past 7000 RPM’s. And the speedometer wasn’t working either. The motor was running fine, and probably around 3500 RPM’s based on my 25+ years of boating. I have a GPS device on my smartphone and it showed I was traveling around 16 MPH. Any idea what the deal is with Tach and Speedo? Thanks in advance.

[Bryden24shp]

Digital or analog gauges? My guess is a ground wire, possibly??? I would sure think its under warranty, being a 2012. I'ld give your dealer or the company a call. You shouldn't need to have to mess with it.
Let us know what you find out!
Good Luck with it!
Bryan

[RAM1961]

Analog. Bentley did tell me prior to purchase they have lifetime warranty, so I've contacted them.

[crspang]

There should be a switch on the back of the tach. 2cyl, 4cyl, 6cyl etc. Or a switch regarding the number of poles the alternator has.

[oldmn19]

This may not be as serious as you think. Before you do anything, try this, the next time your out on the boat. If you feel it's way off or the needle swing back and forth or jumps up to max RPM's. Tap on the glass with the end of your finger, don't use anything but a finger. It works for me when mine acts crazy. I believe it's caused by static electricity. I've started my motor and had it idling and the gauge would show 3000 RPM's or bounce up and down between 2000, and 4000. A good hard tap on the glass and it settles down and may not do it again for month's.

[Jack65K]

There should be a switch on the back of the tach. 2cyl, 4cyl, 6cyl etc. Or a switch regarding the number of poles the alternator has.

+1 - I had the same issue with my 2012 QWC and it turned out to be that the tach was set on the wrong setting. I suggest you get under the helm with a flash light and check the setting on the back of your tach. After I reset mine, it has worked as it should.
Jack