Saltwater series II help needed!

[henryhn9792]

Hi, thanks for reading my post. I have a twin set of 200hp OX66s year 2000 in which one of the motors has a problem. Every time I try and accelerate past about 3500 RPM, the motor would stall and go back down to about 2000 RPM then try and accelerate back up again.

The engine will drive fine if I leave at below 3500 RPM. I think that motor is not getting enough gas fast enough, so I thought changing the fuel filter would help, but it did not.

Any tips or suggestions to my next plan of action?
Also, thanks in advance!!

[TownsendsFJR1300]

My neighbor has a similar 1999, 200 HP two stroke with a similar issue. Single OB on a 21' CC. The engine slowed down, got the blinking alert on the bottom of the tach. A re-start, the red light went away and you were good up to about 4k RPM's

The engine was going into limp mode at about the same RPM's. We replaced the waper pump (it was due) and found a salted up frozen shut (with salt) thermostat. After replacing them the RPM's raised some but still shut down until a re-start.

After speaking with the top tech at my local marina while they were working on my engine, he spoke of salt/mud build up in the heads/cylinders causing the overheating. (My neighbor rarely flushes the engine after salt water use)

We pulled the heads and found SO MUCH SALT BUILT UP, two cylinders were not getting any water...(thus likely the overheat issue and shut down). We spent literally hours scrapping salt and gasket material from all crevices. It should be fully re-assembled in next couple of days.

As for your boat, if its used mostly in salt water, do you flush it once done?

If not, I'd suggest pulling the thermostats and checking for any salt build up and checking the thermostat(s) that they are indeed operating properly. If you can look down into the coolant jacket, you may be able to see how clean or salty it is and go from there...

Good luck..

[jb123]

do you have digital gauges ?
any errors on them if so ? oil or temp to make the drop to 2k ?

[99yam40]

monitor fuel pressures/ vacuum to see if there is a problem with fuel supply