2000 Optimax 225 hp rpm change ( erratic)

[chenson]

Hello everyone. I have a 2000 Mercury Optimax that started rpm change at rpm over 3000. When it does it, it will only go down about 300 rpms, then 10 to 20 seconds later it will come back up to the rpm it should be. Under 3000 it runs perfect. Idles perfect. Starts perfect, and has no engine lights, no misfires. This motor has been updated with new style (blue) air injectors. Fuel rails were rebuilt about 4 years ago. The engine only has 500 hours on it and the compression is like a new motor, very well taken care of.

Any ideas would be appreciated.

 

[Bondo]

Ayuh,..... Welcome Aboard,..... Check the contents of the fuel filter, from anything but clean fresh gasoline,.....

 

[Faztbullet]

Check fuel and air pressures..could be a tracker valve acting up..

 

[chenson]

New fuel filter and plugs, always run 100%gas. I cleaned the mass air sensor. Ran it yesterday. It ran great for the first run out in the Gulf. started acting up again on the way back. the motor has got some years on it. I'm thinking maybe a sensor is acting up. With no engine light it's odd.

Thanks for the welcome and the feedback.