Fuel pump issue:
 

I just replaced my HPFP on my 2012 MCS R56 which has the n18 engine. On random occasions the car will die and not restart. I clear the check engine light (says low fuel pressure) and I pull out the fuel pump fuse (which is never burnt out) and replace it. Then I go to start the car again and its like noting has ever happened to it and it runs perfectly fine. Anyone got any ideas or tips for me? Maybe a relay somewhere? not sure if it matters but my car also has 86k on it.