Dead cylinders wet spark plug

"yamaha 150 v-6

the engine

"yamaha 150 v-6

the engine feels like it only throttles up to half throttle. it starts instantly and runs good enough without backfiring or stuttering. I have 2 dead cylinders that get spark (maybe weak spark?) I know this because they shocked the f'ing s out of me while I was performing the "pull one plug at a time" test. I pull the plugs and the 2 bad ones are oily/gassy. I put a new plug in and it got oily/gassy. I pulled the carbs inspected / drained them, they had a bit of water in them. my question is can the plugs still be getting wet with fuel/oil if the carb is still dirty? what else might cause dead cylinders"

I put a spare plug on the two

I put a spare plug on the two dead cylinder plug wires and observed weak spark. I cleaned up the grounds to the coils and a nice clean spark appeared. I put everything back together and observed a puff of smoke in the V of the block area in the vicinity of the dead cylinders. I carefully removed the head and checked the head gasket but cant see any telltale signs of a blown head gasket.

Which cylinders are dead?

Which cylinders are dead?

bottom two of one bank (cl

bottom two of one bank (closest to water) on one side of the v.

"puff of smoke seems to be com

"puff of smoke seems to be coming from the exhaust cover, I was mistaken and wildly assumed the puff was coming from the head gasket because the two dead cylinders were in the same area as the puff of smoke. I think the rich exhaust leak might have damaged the coil packs or corroded the grounds to the coil packs for that area. Im going to take her out when the weather gets better and see if its all fixed."

"I think you are on to somethi

"I think you are on to something. That exhaust leak is not a good thing. Water can get into the exhaust in the wrong place, and/or exhaust can get into the cooling system."

is that a big job? whats unde

is that a big job? whats underneath that cover?

"Not a big job. This is where

"Not a big job. This is where the exhaust is cooled by water from the pump. They are separated here; as the exhaust leaves the bottom of the block, water is then added directly to the hot gases."

"ok, so I finally got the head

"ok, so I finally got the head gasket in the mail and installed it. Ran real good, finally was able to make a wake again. I idled it around for about 10 minutes in a no wake zone and went to go full throttle again. It started running good and felt a shudder as it went back to running slow. I babied it back in to the slip and saw that I had a few spark plug boots loose. Im going to take it back out tomorrow maybe."