Spark plug issue?

[retC17load]

Hello, new member, and hoping for some insight into an issue that I’ve been having with my two year old F115XA for the last year. Basically it’s this-we’ll be out cruising on lake in our pontoon (2006 Bennington 20 foot) when all of a sudden the engine will just lose power, like not running on all cylinders. The local tech will come out and put new plugs in and it will run fine. The issue is that I went through two sets of plugs last summer in only about 50 hours of operation. We had the boat in storage this past winter and the local shop did the usual spring tune up. Got the boat back in March and only had it out a couple times for short runs, but had it out this past Sunday and the same thing happened. Limped home, tied the boat up and went down the next day just to see if it was still running rough. It wasn’t, took it out for a short spin and it seemed fine. The local guy is telling me that sometimes you just get bad plugs, but I keep thinking that something else is going on, like maybe something is overheating (coil?) and causing this problem. Any insight anyone can give me would be greatly appreciated. Thanks in advance.

[DennisG01]

I'm not the best to advise here, but I don't think it's the plugs, themselves. Instead, what is CAUSING the plugs to get fouled so darned quickly? Is oil getting past the rings? Is the fuel mixture off? Since you're under warranty, I'd just let a Yamaha tech (that has the proper diagnostics... computer, etc) get on it. He'll be better able to figure things out since he can actively monitor things with the computer and, hopefully, narrow things down to the right (offending) system to look deeper into. I don't think you'll find anyone on this forum with a long enough extension cord to hook their computer up to your engine

[99yam40]

which plugs are going bad?
are they oil fouling or something else happening to them?
Have you even looked to which cylinder or cylinders are having the problem?

Does you alarm system work properly?
lights and horn when it should so it can show you if there is an oil or overheat problem happening?
even if the lights and horn do not work, the motor should go into RPM reduction to let you know it has a problem and to stop running it before you do major damage.

could it be old bad gas?