4 Tec engine surging

[FunonH2O]

I have a 2012 Sea-Doo, 180 Challenger! 260hp. I bought the boat used in Oct of 2020 with 95 hours on it. I found out the intercooler was cracked and since I live in Maine, the boat was winterized and into storage. In the spring of 2021, I had the dealer install a new intercooler, new plugs and rebuilt the supercharger. I use only ethanol free gas, no idea if the previous owner did. I used the boat all summer, but noticed an engine surge at lower rpm, less than 4500 but ok at idle. The surge was noticeable but not more than a 200 rpm change. The boat was winterized by the dealer and stored in Sept of 2021. I got the boat out and on the water in May of 2022. Now,all summer, it surges at most all rpm ranges and at max throttle will usually only go to 6800rpm. Once ina while at full throttle it will surge to 7800 but falls back to 6800 after only a few seconds at the higher rpm. Sometimes the surge is so wide ranging at about 5000rpm, that is seems to almost quit. It will accelerate smoothly, but at almost any throttle position, it surges significantly. I still use only ethanol free gas and now, at dealers suggestion, put in k100 at fill ups. Has anyone seen this kind of problem?

 

[POPPS]

Sounds like fuel depravation,,,lawnmower like.

 

[ski-d00]

Change your spark plugs. What you describe is exactly how the spark plugs fail. They can fail very quickly and it doesn't matter how they look.

 

[FunonH2O]

Thanks for the inputs. I will check the plugs, but they were new last spring and only have about 25 easy hours on them, but ya never know. My gut feeling is fuel, almost like intercooler leak with small amounts of water going into the intake, but the intercooler was replaced at the same time the plugs were!!!
Again, thanks for your input.

 

[ski-d00]

Leaking intercoolers don't surge in my experience, failing plugs surge where the surge becomes more frequent. Have replaced tons of plugs that failed at less than 25 hours, some at 1 hour. Checking them will do nothing, they always look great, cleaning them will do nothing, they need changed. Seen people change all kinds of parts who insisted plugs looked good and then change them as a last resort and runs like new. 4tecs eat plugs, always change plugs first.

 

[FunonH2O]

Leaking intercoolers don't surge in my experience, failing plugs surge where the surge becomes more frequent. Have replaced tons of plugs that failed at less than 25 hours, some at 1 hour. Checking them will do nothing, they always look great, cleaning them will do nothing, they need changed. Seen people change all kinds of parts who insisted plugs looked good and then change them as a last resort and runs like new. 4tecs eat plugs, always change plugs first.

 

[FunonH2O]

Thanks for that information, would not have guessed plugs. Will get 3 new ones tomorrow. Will post if it works

 

[FunonH2O]

Replaced all 3 plugs. It seems to have helped a little bit, but it still surges in mid range rpm and tops out at 6800 rpm at about mid throttle position. Pushing the throttle to max does not increase the rpm initially. After about a minute at full throttle position, the rpm will slowly creep up to about 7200 rpm. Not sure what the normal max rpm is for this engine, but the 215 hp engine in my speedster would easily reach over 8000.