Thank you for the advice you all!

I’ve noticed that my teak swim Platform moves up and down while the boat is sitting still and waves and swells crash in the back. I can pick up the back of the swim platform and move it up and down probably an inch and a half. The cotter pin’s are a little bit loose, and I have drilled them out...

Built a rack for my props. I think I may have a problem ...

Like this. ...

I’ll try and take a pic of them when I go back out to the boat. Follow the power feed from the medallion, and you will see them. They take small glass style fuses.

2008 MMDC Delete and Gauage Replacement

I had a similar issue this year. It turned out to be corrosion on the two fuse holders going into the medallion unit. They are round, about 2 inches long. Replace the fuses, clean the contacts inside the holder, and try the system. It worked for...

All of the manufacturers suggestions keep the prop at a maximum of 14.75 diameter. You have no problem with a 15”?

I literally just went through exactly the same thing on my Star. Replaced all the running gear, but is still have a slight vibration at 4500 rpm. I’m starting to think it could be the dampening plate between the trans and engine.

Currently have an OJ 812 (14.75 x 15.75) on my X- Star (2004, LQ9 6.0L, 385 HP).

It was damaged after hitting a stump, so I’m looking at replacement options. The prop has been great in the 4 years I’ve run it (standard ballast, wakeboard 30% of the time). Night and Day difference...

Sounds like fuel pump to me. See if you can watch the pressure when you put it in gear and then under load. I bet the pump is weak.

Yep. All mounts are tight. Even checked the mounting bolts into the stringers. They are tight.

Could it be something in the trans? dampener plate? Clutches going bad? I have had the boat for 3 years, and i has 600 hrs on it when I bought it (780 now). The prop was always hard to turn before...

Yes it did. Shaft is perfectly centered in the log.

So I got it all fixed. New strut. New prop shaft. New Prop.
I aligned the engine and trans, and have the alignment to .0015 on the coupler. I can spin the prop with one finger.

Took it for a test drive. As I get up to 25 mph, and 3500 rpm, i can start to feel the boat vibrate...

Remember the 4 basic needs of an engine: Fuel, Spark, Air/Compression. I would first check the fuel pressure. Needs to be 55 to 60 psi.

Then check to see if you have spark. Pull a plug after turning the motor over. If it’s wet from fuel, then you don’t have spark.

...

Updated.
Ordered new shaft and strut. I’m in the process of removing the old running gear. The drive shaft nut at the coupler would not budge at all. Even using a pipe wrench with a cheater bar, it would not turn. Someone must have used red loctite on the nut (and there was no set screw on...