2006 X5 Diesel intermittent cold start problem

[opienor]

Hi guys!

Well I´ve understood I´m not the only one with X5 start problems...
Never had any problems with my car, but a couple of weeks ago I started having problems starting it. It seems that the colder it gets outside the more pronounced the problem is. Here´s what happens:
I turn the key and all is fine. Everything lights up as usual and the DDE light indicates glowing. Then starter cranks just fine but there is no sign of ignition. I then have to completely turn the ignition off and try many more times before the engine suddenly fires.
I notice that every time the engine fires there is an extra pump buzzing sound when I engage the ignition. Hence it appears that the diesel pump fails to function every now and then. But what causes this? My car is at an official BMW dealer as we speak but they haven´t been able to recreate the problem and have no clues. The outside temperature is of course much higher now, so the problem doesn´t show up. Needless to say I´m getting a bit frustrated. Any ideas much appreciated!!