Misfiring on cylinders 2 and 4 - carbon on plugs.

[VTSeaRay]

So, I had some alarms go off - Eng Oil Pressure Sensor and pitot sensor (?) failures. More info said to head to port immediately, and see a local dealer (?) Analog gauges looked good, I checked engine oil, that looked good. Strange. I have been fighting what I thought was water in my gas the past 4 seasons... putting in treatment, and it seemed to fix it, once she warmed up. So, at the shop, they looked at it, and found the misfirings on the diagnosis. A compression check showed compression was good in the cylinders. So, pulled distributor/rotor. badly corroded. surprised it even started. Swapped them out. Reading online about this - seems it's very common.. This was an easy 30 minute fix. It took me almost half of that to label my plug wires! I'm going to include it in my yearly maintenance going forward it's so easy. While I was working on it, I replaced the impeller as they said it seemed to be running warm. The impeller was incredbly good looking. Almost looked brand new (engine has just over 150 hrs on it. They showed most of my running time was in the 1500-3000 rpm range. ) . But, I swapped it out while I had it all apart. using the Mercruiser impeller kit. Filled the lower unit back up with new oil and she's ready to put back in the water for a test.