2000 Model 200 Opti acting up

[Lizzy K II]

I'm having an issue with one of my 2000 model 200 hp. Optimax engines. The motor starts fine and runs great below 3000 rpm. However, when you try to run the motor above 3000 rpm sometimes it starts to fluctuate and stall. It never stalls to the point where the motor will die, but the rpms will rapidly fluctuate. I have a DDT scanner and no codes or check engine lights are shown. The only fault codes that are occurring are battery faults. I had the alternator checked and it seems to be working properly. I also made sure I had a good battery, and I even moved the battery right next to the motor and connected it straight to the cables coming out of the motor.

Does anyone have any idea what might be causing this? About a year and a half ago I had all the diaphragms in the air and fuel regulators replaced on the fuel rails as well as the tracker valve.

I'm at a loss as to what might be causing this.

[boats.net]

Need to have fuel and air pressure test run on it.

[Lizzy K II]

I'll check the pressures this weekend and post the results. Would it be beneficial to test the pressures while up above 3000 RPM in addition to checking them at idle?

[Lizzy K II]

What do you think?

[wallnuts]

Lizzy. I had the same problem ...try this...when you are running over 3000 rmp look at your fuel primer ball for that motor...it might be sucked in. Which means you have a restriction in your fuel line...enough fuel will pass through at lower rpms .But not above 3000...when I inspected my fuel lines at the Stern of the boat, where the lines leave the hull and travel to the motor about 4 or 5 feet. They looked like clogged arteries...I asume it was from the Sun beeting down on that section of fuel Line. They were clogged with dried up fuel....I changed the lines and motor came right up to correct rpms.....hope this Is your issue because its a non expensive repair......good luck.

[Sidenberg]

Curious where you got the DDT scanner and at what cost?