On saturday my 2003 325 auto would not start. When cranked initially, it attempted to start and just died. Further cranking was futile. About 15 minutes later, I cranked it again and this time it started but with a rough idle at first and I could hear air being sucked in the inlet manifold, sound you get when the air filter is removed on a carburator engine. After a few minutes the car was idling normal. Prior to this, the car was not used for 5 days and parked on a slight incline with the front higher than the rear. Could this have caused the fuel to drained back into the tank? Or could I have a problem with the fuel pump? I have travelled aproximately 100Km since without any sign of trouble. Thank you for your assistance. Regards.