560SEL- hot starting trouble
 

'87 560SEL 322k miles in really excellent shape. Problem is, does not start or idle well if hot. Example: Run to store for oil and filter. In store ten minutes. Come out and car will crank forever if you just turn key (cranking speed good). To get it to start, turn key on for 20 seconds (seems to help, but not sure), hold pedal at least half throttle, start engine. Maintain 2000 rpm for minute or two. Engine may or may not start ok. Will probably be running rich-real rich, lots of black smoke. If you forget, have to hold pedal to floor and let car run at 500 rpm until it clears its throat (it seems). That can take several minutes. Car starts great when dead cold. Seems to start ok if sitting for an hour or so. This happens in dead cold of winter or in warm weather. I tried replacing the OVP relay, but it did not help. If vapor lock or low fuel presure, I would expect it to be lean, not rich. New plugs did not help. I am befuddled. TIA.
BobK

One of my 560's was doing the same thing and I actually found that after I changed my wires, cap and rotor she fires right up regardless...have you checked the wires/wire ends? and also have your coil checked . Mine was found to be weak and I just replaced it last weekend which also helped with the throttle response issues I had. 322k miles and kickin' huh? MAN! I thought mine was doing good with 219k on one and just over 200k on the other. Your car gives me even more hope! :)
Good luck...

Alan

Sounds like the cold start injector is operating when it should not. When the engine is warm the cold start injector is not needed and should not operate. When the engine is cold it is needed, but only for a few seconds. If the injector is open extra fuel is being delivered to the engine causing it to run rich, or in your case so rich that it wont even start. Try removing the connector on the cold start valve and see what happens. It is possible that the cold start injector is leaking or sticking open. I would pull the plug and see if there is any difference in the way it starts.