Greetings all,
I've gotten a lot of good information from this group so I feel obligated to post a solution to a problem I was having.
1995 S320 would start good cold in the morning or after cooling off 2-3 hours after running. The car required at least 2 extended attempts to start anytime after 5 minutes running or more.First it was suspected that one or more injectors were leaking down into the cylinders creating a pool of fuel that would make it difficult to start and possibly this pool of fuel would evaporate several hours later and the car would start fine. Next, the O2 sensor was changed thinking it was sending a mesage to the brain that it needed to run full rich.
Neither of the above scenarios was the case. Upon pulling the vacuum line on the fuel pressure regulator, I saw fuel drip out of the vacuum line! Appears that the diaphram failed. Changed the regulator and it now starts perfectly, first time, under all conditions.
Hope that helps someone, Bob