sputtering until warmed up?

[speedster32940]

Newbie- first time jet boat owner (lifetime boater) with a 25 hour 2008 Speedster 200 (twin 155hp) I just bought. My question is about the test drive we took. The engines started up fine and idled out to the river fine, but when we got it up on plane they seemed to be intermittently caughing and sputtering with the tach's jumping between 5k and 7k rpm. This lasted for about 5-10 min. until the engines were warmed up & then everything seemed fine after that.

Overall it is in great shape, and has had the 10 hour service with no problems. The boat has an extended warranty until July 2010 and I am thinking that I will drop it off at my local dealer to have them diagnose any problems. My thought was that it may have some water contamination in the gas line.... Maybe I should install a water separator fuel filter??? Any thoughts???? Thanks!

 

[DonoBBD]

Ya I would think the plugs. Long idle time can load up the cylinder and take the plug time to work it off. Once the plugs were up to temp all is fine. Could go to a hotter plug if you wanted but cooler water one day and it will come back.

IF EFI you could read the piston wash and lean it out a bit.

Cheers Don.