Plug Fouling...

[jaxxed]

Newbie question!
I (newly) own a '00 LRV with a 947 purchased with 128 hours and well maintained. After a few months of flawless running, this week I was in the middle of a ride and half the engine just "went away". I was cruising a 50MPH and could not get over 25MPH, RPM's would not come up and I thought I lost a plug wire or such. I had spare plugs on board and swapped them on the water, and found the forward plug was fouled comletely closed. The new plugs solved the problem until about 45 minutes later when the exact same thing happened and required me to swap out another front fouled plug with my remaining clean one to get home. I pulled the boat and did a compression check to see if a bad ring may be the culprit but she's healthy at 135 and 145 PSI with the fouling cylinder the tighter one. Aft plug looks fine.
What next?

Thanks

 

[scooper77515]

Copied over from your OOPS! thread...

Are you fouling at high speed or idle?

I had the same thing happen to me a couple times in the past week or so. It would run great at high speed, but if I idled around for a few minutes and then gunned it, it would hesitate and then eventually after it burned the plugs clean, it would pop out of the hole. Just the first time I gunned it it would bog, but the next time, it would run fine.

Then one morning, I take it out, starts right up, and runs like crap, like it is on one cylinder.

Swap plugs, and I get no problem, until I idle it again.

I leaned out my idle mixture screws by 1/8 turn (actually, put them back to stock 1-turn out configuration), but haven't had a chance to run it to see if it fixed it.

Did the same thing on my XP a few months back and it now starts immediately WITHOUT priming OR choke, and and without having to "turn over". Even when cold. It just lights right up when I touch the button, and doesn't foul the plugs.