Outboard running RPM'S

Maddie'sDaddy · 06-21-2007, 05:27 PM

I have a mid to late 90s force by Mercury 70 hp outboard and its hooked up to a tachometer, runs good but my question is my tach needle tops out just after about half throttel, and stays that way untill i slow to below half throttel, its max is 8000 rpms and the needle burries, is that normal for a small outboard? My speed shows about 25-30 mph, its a fairly large boat for the smaller motor

Thanks for any input you might have

MD

GSD · 06-21-2007, 05:59 PM

MD, it sounds to me like you have a tach problem.
Looking in the specs. of most 70 HP range outboards, 6000 RPM is the maximum running range.

You might need to contact the manufacturer to verify proper wiring.

Bill {GSD}

Maddie'sDaddy · 06-21-2007, 06:38 PM

Thank you bill, thats kinda what i was thinking, i will check online and see if i can find the scumatic.

MD

ampersat · 06-21-2007, 08:56 PM

My tach (which I actually need to install one of these days) is a generic unit with a selector switch on it to match it up to a variety of motors. My guess is yours is set at twice what it should be (showing 6k when it should be showing 3k). Good luck getting it resolved.