I have a 2015 mercury 150 four stroke with 185 hours on it .
serial number: 2B130092
I live up near Buffalo NY and yesterday I was winterizing the motor . Removed spark plugs to fog the cylinders and noticed the plugs are black and sooty . I attached some pictures. This is the fifth summer I have used the boat and previous times I winterized it the plugs were the normal tan color. I run only non ethanol fuel , also when I removed the prop to drain lower gear case lube the inside of the prop and the washer and nut had that heavy sooty black stuff on it as well . Any idea what could be causing my issues. Plugs were replaced spring of 2019 so two summers on them . Could it be because I fog the cylinders ? Thanks for your help . I bought the Mercury service manual from Don and there is really nothing in it to troubleshoot the plugs .I use Mercury 4 stroke synthetic blend 25w-40 oil since new .
Jim Kaz
kaz89@verizon.net