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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3976
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2000 yamaha waverunner, xl700. This pwc runs great,

Customer Question

I have a 2000 yamaha waverunner, xl700. This pwc runs great, but always fouls plugs with oil. I have tried several sets of plugs, (exact plug that factory recommends) Now, it's getting where it doesn't want to start, or you can't run an hour, without changing plugs. So, a few questions, Does High or Low speed screws have anything to do with oil/mixture? I use TCW-3 oil, but is there a TCW-3 oil that burns cleaner? And if I decide to bypass, automatic oiler, and mix my own (which, I really don't want to) can you lead me with some good instructions (pics are appreciated) on how I can go about doing this.
A little history on this pwc. I have checked compression last fall, and all is well. Both spark plugs, look the same, (coated with oil). I have 2 waverunners, and this one always smokes more. I have had bro***** *****s, and replaced both sets this spring, thought I had oil problem solved. New reeds, ran probably 2 tanks of fuel through it, (definetely, should have dried and blew out cobwebs), but am still getting fouled plugs. I do believe, I also ran some sea foam, through carbs.
Please, help, as going on vacation, next week. thanks, Shannon
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

With the engine burning so much oil, since it goes through the carbs the engine is flooding. You can adjust the screws slightly, but this may not solve the issue, most likely the carbs are going to need to come off the engine and be rebuilt.