1990 Mercedes-Benz 560SEL Q&A
1990 Mercedes-Benz 560SEL Question: will not stay idling
These vehicles have a mechanical fuel injection system that is very susceptible to vacuum leaks. There are also some adjustments that need to be performed in a sequential order for everything to operate correctly, so if you're not familiar with how the system works, you may be better taking this to a MB shop. However, here are some tips. Check for vacuum leaks, especially at the injector seals. Fix any you find and make sure the fuel mixture is set correctly. This engine has an idle valve that controls the idle speed, it may be that the valve is sticking or bad. Also, check that the throttle body is cleaned and adjusted properly. - Bret Bodas
Check the fuel pressure relay, it must be seated very snug in the socket. Most times this the problem - Visitor
Its actually a 1986,it idles really fast. What can possibly be the cause of this?