Weird Sound, Capped at 6k RPM, Bad Accelration

[Chasedouglas]

Afternoon JBoaters,

I recently purchased a used 2016 Yamaha FSH Sport.

Shes been running great the last month or so, no complaints at all. But yesterday I had her out wakeboarding and surfing with a few buddies and the engine started to make a weird sound (almost ratting and completely different than normal). The boat also will no go over 6000 rmps even at full throttle and she caps out at about 27mph. I’m not sure what this issue could be, I check the intake and clean out and it was all clear. I ran it today to troubleshoot and the problem persisted.

Has anyone had this issue, or know any possible solutions?
Thankyou!

 

[zipper]

Check the sparkplug wires. One may have come loose. When were they changed?

 

[lazergeek]

I would change plugs regardless of age, I have had some fail at only 20 hours.

 

[FX195]

Does it have the SVHO motor or NA?

 

[sunbyrned]

If the above suggestionsI don’t pan out, I would encourage you to consider pulling the pumps. Sounds like cavitation to me. Even though you checked the intakes and clean out ports, I would recommend pulling the impellers out and reinstall them. Something could still be in there that you can’t find or see. Even if nothing is found, I personally believe the splines on the impellers get out of sync. Here’s a video on how to pull them out if you want to give it a try.

 

[Chasedouglas]

Thankyou all for the help, my first step was changing the spark plugs and we found that the 2nd plug from the front had a tip completely break off, I replaced all the plugs and she’s running great!

 

[leftcoasterfl]

Good find there...I had a similar issue before in my truck (the plugs center electrode was loose).

I never ceases to amaze me the problems motors have...