BMW X1 18d sdrive; cranking but not starting

[toninu01]

Hi,

I got a 2011 bmw x1 18d sdrive which after 2 weeks of not being used is giving me problems.
At first it started after a while and worked ok.
the following evening it started after a very long time (occasionally) but only gets to 2.5k revs. when i remove my foot from the gas pedal engine stops.

does anyone know whether this is a common fault or any idea what might be wrong?

air filter looks clean
fuel does seem to be going in when i loosened on of the metal pipes going into the injectors

thanks in advance