I am having problems with my late 80's 300E. Here goes: The car will be running fine, then I will turn the car off at some point during the day. Then when I try to start the car soon after turning it off, the engine will turn over but not start. Then after the car sits for some unspecified time, it will start again as though nothing is wrong. Less than two weeks ago when this happened my mechanic replaced a rather costly fuel pump relay to try and fix the problem....it did not work because the car did the same thing yesterday and would not start till this morning! When the car is running, it performs just fine.. Please give me your advice, thanks so much!!!