View Full Version : Choke/stall @ 6000 rpm - 2003 Mercury 250 Optimax

04-19-08, 11:28 PM
Just bought a used 2003 seadoo utopia 205 with the 250 optimax. Boat was winterized and fired right up early April. Problem is that when I "gun" the boat (to get a skier out for example), it starts going and once I reach ~6000 RPM, it seems to choke/stall and I definitly see a significant loss of power in acceleration. If I take it slow, then I can easily take all the way up in rev and hit 45+ mph. I noticed that the boat tends to smoke "heavily" (white) when I am in that choking zone. It is quite hard to describe but the sound the boat make is very clear of something not right (unifiorm accelerating sound and then an "up and down" engine noise as it is lack something: fuel, water, ...)
No idea where to start looking.
Would anybody have an idea (If you are still awake after my 2 pages explanation :) )

04-19-08, 11:49 PM
It sounds like your temperature sensor in the block went out. The 240 hp Optimax M-2 engine is self tuned by several sensors that send input signals to the ECM (electronic control module), which makes automatic adjustments to the engine for optimum performance.
When the temp sensor fails, it causes the ECM to think the engine is cold, so it never leans the engine out after it starts.