[octane]

this is my first boat with tach, so I'm asking the experts for help!

I have a 2008 merc 4 stroke EFI 115hp with faria gauges, when I was doing my break in, the engine would idle at 1200-1300rpm, which I though was high, but decided to check the service manual when I would get home.

After break in, I was doing a top speed test to determine what change I should do to my prop, and I got 41mph @ 6900rpm.

from the service manual, my engine should run at 700rpm idle speed, and 5800-6400 max rpm, with the cutoff at 6500rpm.

are my gauges messed up? would the tach be set for an engine with 3 cylinders instead of 4 give me this extra rpm reading?

thanks

I'd bring it back to where I bought it, but it's 3 hours from the cottage

[hkeiner]

The tach gauge has a switch on the back for setting the number of "poles". This setting varies with the motor, and if set incorrectly the gauge will show the wrong RPMs. The below linked guide may be of help to you. While it is from Teleflex, it would apply to Faria gauges just as well.

http://ww2.tflx.com/PDF/99320.pdf