Try this: press fuel pedal a little (around 1000 rpm) and try rotating it. Is it becoming smoother? if yes then you need a new pump. I just replaced it last week. The one I had was 120 bar, the one I installed is 130 bar, stronger.
However, first thing you need to do is to check the fluid level, if ok then lube the universal joint.
Here's a helpful thread: http://www.xoutpost.com/bmw-sav-foru...nt-photos.html