It's hard to believe you've done nothing in 8 years to protect your "$10,000" dollar engine. I see this all the time. Sensor's that are shot, turn key enrichment not working correctly due to a bad temperature sensor, causing it to smoke and foul plugs.
These engines must have yearly maintenance or in the long run, you'll find yourself looking for parts. Outside a dealership, have you tried to find parts for this boat? I only know of one respectable web site that is reasonsable and will not rip you off.
It is a total loss cooling system and because of the sensors that adjust the mixture to keep if from building deposits, it'll run for, as we see at the moment, 8 years without maintenance.
But, ...............you are going to greatly reduce the life of this engine. Taken care of, this engine will last upwards of 15 years without a major overhaul. Your engine? We don't know yet. Keep us posted in the future as to how this engine contiues to run. Cheers!
Legal Information: This SeaDoo/Merc 240EFI JetBoater's Forum is NOT affiliated with any JetBoat companies. It is merely a place where 240EFI Jetboat owners can post questions, answers, and opinions. Any and all comments, recommendations, suggestions, and/or any information seen on this forum is protected by our Rights of Freedom of Speech.
This forum can not be held responsible for information that is learned here that may cause harm, or financial loss, to any person(s)and/or JetBoat(s) alike. Please use your common sense and post/read responsibly ... Thank You and Enjoy!