Rough idle on restart
 

I have a 1986 560SL and am hoping someone can give me an idea if there is a typical adjustment or part that could be causing my problem. Cold start the car starts and idles perfectly, however when restarting when warm it will miss or chug like it is probably too rich. If you step on the accelerator slightly it clears up in a matter of seconds. I haven't actually had anyone to start it for me so I could see if it is smoking black from the exhaust, but I expect it is. When I say it does this for seconds, it is literally 5 to 10 seconds or less.

Same exact problem
 

Same problem on my '88 560sl. It happens about one in twenty times, typically if the car's been sitting for a half hour or so after being driven. Never on cold start. I thought maybe a temp sensor. Would be interested in what you find.

David

Sounds like the fuel return check valve. It is supposed to maintain fuel pressure after engine shut down to prevent vapor lock on warm starts.

shane83SD

Thanks for the reply.

Where is the fuel return check valve located and is it difficult to change?

location of fuel check valve.
 

It screws right on to the pump, at the back of the car right below the fuel filter. You might also check for leaky injectors, possibly by checking the plugs after shut off to see if any of them are wet.

Thanks for the info, I will check into these possibilities next chance I get.

I really appreciate all the help I get from this forum!
Thanks again.