Looking for help, 04' Yamaha 225 vmax ox66 pulled power head and lower unit to fix broken exhaust manifold guide. Fixed everything, got everything put back together. Took it out to the lake for a test run. She started right up on 1st bump of the key and purred like a kitten, actually idled better than it ever had, let it warm up fully and went to get on plane, boat starts missing between 2500 and 3000 rpm, will not get above this, almost like its some type of safe mode. Checked plugs for fouling and checked compression, both are fine. Anyone have any ideas?

Wow, there were a lot that had to go together right after pulling the power head and lower units. I’ve never done this on my yami, but I wonder if you can hook up some sort of computer diag tool to fire off injectors and disabling plugs one at a time.

I’ve done this on the Evinrude where if you disable one plug at a time, and you notice the idle change, then you know one cylinder is not good. It’s hard to detect at idle, but.a cylinder not firing will show itself at higher rpms. You can do this by manually removing the plug during idle and replacing it to go to the next one. That’ll give you an idea if it’s a non firing cylinder. The other could be safe mode. But typically, it’s lower rpms (like 1500). Yamis may be different, but that sounds high for a safe mode. Good luck Tim

I had that same motor acting similar once, and it was the fuel line kinked and crimped right where it entered through the lower cowling with all the other wires and stuff restricting the flow of fuel.

Hey Guys,

Just thought I would share what we found with my boat.. It was loose ground wires and bad plugs.. Fixed it right up.. Now she runs like a scalded ape..

awesome
thanks for the update

glad you got it going and congratulations on a job well done!

Thanks for following up with what you found. Nice work!