New to the forum (although i have owned gators for quite a few years). I recently purchased a 2011 825i from an auction. It was a decent deal considering options and condition. The engine is running rough and maybe misfiring. I have been going through the systems both to familiarize myself with the current state of each and also to find any potential problems. This is my second gator so it can be a long term project. I checked fuel pressure last night (inline just after the fuel filter, which is new). I am seeing about 40 psi from the fuel pump (a little low - i have the service manual) but when the pump stops the pressure immediately drops to 20 psi and slows leaks down to 0. Is this normal? Is there a check valve in the fuel pump/system somewhere that should be maintaining pressure? I know the fuel pressure is important for the performance of these engines. Thanks in advance for any help you guys can be. Look forward to from learning the folks on this forum.