As you may recall a few weeks ago I posted to the group about a problem I was having cold starting my 1988 300SL, some one posted a very useful link to a site about the fuel injection system used on these cars. Using the info from this site and some wiring diagrams from the Mitchels work shop CD (does anyone know of an official Merc manual for the 300SL ?) I traced it back to the overvoltage protection relay, which it seems controls power to both the cold start injector and the cold start air bye pass valve. Changing the fuse on the relay fixed the problem and the car is running like a good un. Now to sort out the stereo.
Simply posting this so it is in the archive should someone need help in future
Ben '88 300SL