Really high RPM's 1999 bow rider 3.0 Merc

[mikeybo2004]

New to boating. Been out with my boat only twice. Learning lots but still have a long way to go. My second time out yesterday I realized that my tach is reading really high. Idling at 5000 and gets over 7000 when cruising. The engine does not sound like it is racing. When at idle it sounds normal. Had someone tell me that the engine sounds great. Oil pressure and engine temp are within normal/acceptable limits. With my limited knowledge it seems like I have normal power when accelerating/cruising. Anyone have any ideas of what this problem could be?

 

[tpenfield]

:welcome: to iBoats

The tachometer is broken. Not sure if there are any tests you can run, but you should probably look into getting a new one.

 

[mikeybo2004]

Thanks for the reply. Seems kinda obvious now that you say it. Doesn't look to be too hard of a job for me to do.

 

[QBhoy]

Agree. Check tacho. It would wreck the gearbox going into gear at 5000rpm. If not, you would know all about it. It would be screaming at those revs.

 

[TyeeMan]

I'll lay you bet that if you rap on the face of the tach with your knuckle (when it's running) a couple times and it'll settle down to proper rpms.

For unexplainable reasons my current boat and my last boat did the same thing. Tach needle would go strangely high, rap on the face of it once or twice and good as new. Might be ground problem? I don't know.

 

[nola mike]

You can buy a shop tach or my dwell meter (remember those?) can tell you the rpms pretty easily. Agree with the above though. Your outdrive would grenade shifting at 5k rpm. No way it's idling that high. Check and clean your connections at the gauge and the distributor. Also the tach may have a switch on the back for the number of cylinders in the boat, if set for a 6 or 8 cylinder it would read high on a 4 (I think, might be the other way around though).