I am having trouble starting my 240D if I try to restart after driving for a while. It just acts like it is not getting fuel. After repeated attempts it may start but will not run much faster than idle speed even at full throttle. If I let it set for about 10 minutes it starts and runs properly. I just bought the car and have notices that the fuel in the pre-filter looks very dark. I ran Diesel Purge through the system and the return flow turned the Diesel Purge black. Do I have air in the system, is the fuel contaminated, or is something else going on.

Any help you can give would be appreciated.

Bill