Engine idles then races

[<luckydog>]

I have a Yamaha 200 Saltwater series engine. While at idle it seems fime. When setting the rpm to 3500 it will all of a sudden increase to about 4900 on its own, then drop. Any ideas what could be causing this to happen?

[<boats.net>]

It would be hard to say without checking it out. some boats will not get completly on plane if throttle up slow and will give you a sling shot effect when breaks onto plane. But you need to have the engine checked out, if it is an OX66 model it may have low fuel pressure or O2 sensor problem

[<Ed McKenna>]

At the risk of sounding like a broken record from other posts...

When at 3500 does it seem like it's running like crap? Or is it running great, and it's just like it was given more throttle?

Need more info to help diagnose, but if running like crap at 3500 then could very well be temp related. These EFI saltwater series are wicked sensitive. In advance of your reply, if runs poor at 3500 but OK at dock, I would check thermostats and purge valve.

Ed