300xs. Problems

[hp1050]

Have you had it to a Mercury Dealer yet to look at it with there diagnostics?

[Revolution141]

Update. I have picked up no. 5 piston! Ran again and straight away getting on plane noticed things just weren't right. Idled back and pulled boat out. Pulled plugs at home to do compression test and found plug in 5 to be bent. Pulled head and piston is trashed all around the skirts.
I had it on merc diagnostic tool a while back but it showed nothing, air/fuel fine. Mind you this was all on trailer just free revving.
when I said I was wot for 40mins I mean we ran say 15min then stopped at beach for a while then another 15 then stopped etc. Would have been 40mins total but.
Like I said before the most frustrating thing here is things haven't been right from word go and now 150hrs and 3.5 years down the track I have to re build out of my own pocket cause as far as merc are concerned she is out of warranty.

[hp1050]

Revolution what is your engine serial number?, from your comments I assume that have you spoken to Mercury?

[native2]

I am sorry for your loss. My 300xs has been very good to me.... During your rebuild, I would change no. 5 coil and clean all fuel/air injectors. Carefully inspect all of the wiring plugs and harnesses. Open up the VST and make sure it is clean. I may consider replacing the TPS after reading about the troubles you have been experiencing. I would not want to go through it again after a fresh rebuild. A coil and a TPS are cheep compared to a rebuild.

[Revolution141]

Revolution what is your engine serial number?, from your comments I assume that have you spoken to Mercury?

IE050326
have only dealt with local merc dealer whom I purchased engine from.