Hope to get some info and help here. Seems like a lot of knowable folks here. Anyway I got a 1999 15hp Johnson. I just bought the boat and first time out it was hard to start. Once I got it running it ran great going down the river but would die if you tried to idle. I removed the carb and went through it with a new carb kit. Still wasn’t right. Eventually I found that the plastic top of the carb is sucking air. It is visibly warped. I sprayed carb cleaner around the gasket with the engine running and it would change rpm every time I sprayed. The scary part and my main question is about my spark plugs. I put new plugs in the other day and the old ones looked ok and both looked to be burning similar. Today I removed them to do a compression test (while waiting for my new plastic carb top to come in) and noticed the bottom plug had a gray film. Looks like when water mixes with oil. It had 110 psi on both cylinders? If it was a head problem causing this wouldn’t I have low compression? It probably has less than 5 minutes of run time since I changed out the old plugs that didn’t have the gray film on them.
