380 running rich

[pete380]

I have an 85 380sl that is running very rich. Black smoke pours out the tail pipe if I rev the engine. I have had the fuel dist. replaced, new vacuum lines and check valve. All of the plugs get fouled not just certain cylinders. There is a strong smell of unburned fuel coming from the exhaust. Any ideas?

Thanks

[London380sl]

I had a similar situation where the exhaust was also running black and there was always a smudge on the pavement where the the exhaust was. In my case the issue was the o2 sensor was disconnected. Put a new one on and the car has run perfectly since.

You might want to check to see if that is an issue. Its a fairly cheap repair and they should be replaced every 60K.

[ctaylor738]

If you had the FD replaced, the shop should have adjusted the mixture as part of the replacement. You may have a rich mixture adjustment, a leaking o-ring on the FD shaft, a bad cold start valve, a bad warm-up compensator, or excessive fuel pressure from a pump on its last legs or a bad pressure regulator, or any of a half-dozen other issues. All of these are easy to check if you have a gauge set and have worked with the system before.

Do a search, lots of posts on this sort of problem.

Good luck.

[pete380]

Thanks for the help. I replaced the O2 sensor and the car runs great.