Grandsons 1990 240 DL. He said the old girl has been blowing greyish smoke out of the exhaust for the last week or so. Does it even when fully warmed up but more when it is cold. Today I took a look at it. Starts up fine, idles ok but has an intermittent miss when cold but smooths out when warm. Hot or cold there is grey smoke out of the exhaust and it smells like the car is running fairly rich. After letting it run for about a half hour while checking things out it still had noticable gray smoke that smelled like unburnt fuel out of the exhaust. Later after it cooled I checked the coolant and it is fine, but the oil seemed rather thin, and smelled more like gasoline than oil.

So....what could cause it to run rich, miss intermittently, and cause the exhaust smell like unburnt fuel. No codes or check engine light either. I'm thinking possibly a stuck fuel injector. The fuel pressure regulator is brand new.

 

Pull the spark plugs and check each one. If you have a sticky injector, I would expect one of them to be black and sooty while the others should be a lighter color. If they are all black and sooty, then your problem is most likely a stick injector. Does yours have a cold start injector? If it were to stick open then it could lead to all plugs being sooty.

 

I'll pull the plugs as soon as I get time, but yes it does have the cold start injector, I'm kinda leaning that way as the cause of the issue.