I did a search on the forum and couldn't really find anything to help. I have a 1995 50 Hp Johnson carbeurated 2 stroke 2 cyl. I've only had the boat/motor for this year. Most of the year I averaged running it 1 or two times a week at least. motor ran perfect. Now, the last two times I have had it out, at least 3 weeks between runnings, at startup she blows a ton of smoke; then once I run it for a minute or two at some decent rpms, it's fine for the rest of the day. I talked to my local shop, and he believes from what I'm telling him that it is the fuel/oil pump check valve failing and the pump needs to be replaced. with frequent running, it won't be a problem, but If I leave it sit for a few weeks, oil leaks through the bad check valve and starts to fill the carbs & will run oil rich until they get cleared out. Longer it sits, the more oil can flow into the carbs. If I leave it sit too long, the carbs will be completely flooded and will need to be cleaned out by hand before it will run. Made perfect sense to me; does this jive with everyone else? Anything else That could cause oil rich conditions after sitting for a couple of weeks? I do notice that everytime I go to start I need to reprime the bulb in the fuel line as there is no pressure. Could it be a bad anti-syphon valve in the fuel system letting the fuel drain out? the oil system stays pressurized all the time... This is my first motor, so please bear with me.
. if I let it sit for to long I have to remove the airbox and pull the drain plugs. messy at best so I try to run it 2 or 3 times to manteo and back every week