So I went on a long journey (150 mile round trip) in my 1 series on friday. Got home and all was well, no issues , no lights etc. Got back in the car an hour later, picked up my friend, went over a bump and the engine light came on, I was limited to 2500rpm. I left the car, went back to it the next day and it drove fine for 10/20 minutes, no lights etc I didnt drive the car again until I went on a very short journey yesterday, the car cut out and has not started again since. A friend has plugged it in and I get the 4b90 code. Now I know this code can be a manner of all items but where do I start? I have ordered a low pressure fuel pump and a fuel filter and they arrive tomorrow, can I do anything else until I get these changed? Also is there a fuel pump relay or module on the E87? All help is appreciated. Just to add - we took the plastic cover off to expose the rail and injectors and it was all dry.