Hey Guys, can anyone confirm if this part is a fuel pressure regulator by the filter housing? Or some check valve? I know Bimmers have pressure regulators in their filter housings. Has anyone seen this fail? I'm hunting a 2-3k hesitation & hard start problem... History: 02 R53 w/ 55k mi on the clock @45k mi, changed the ff: OE Fuel filter, rail side fuel pressure regulator w/ vac tube, injector O-rings, plugs, leads, coolant temp sensor, Crank Pulley to ATI, OE belt & tensioner. @50k mi, swapped the fuel pump Symptoms: Occurred suddenly.... On a 120mi drive last week, car suddenly loses power & hesitates at 2-3k. And now struggles to start. Swapped new OE NGK plugs, no improvement on hard start. All 4 wires have good spark. These are how the 10k mi plugs looked....pretty normal... Batt is constantly hooked to a trickle charger. Crank is good. Pump primes but I've lately heard a few ticks on the filter side upon priming. Maybe 5-6 ticks or taps. Hooked a pressure gauge by the rail...8psi...not 52!!!! Removed pump & filter assembly for external inspection. The 5k mi old VDO pump works! No cracked nor split hoses! BPV spring is fine. Put everything back in, pump primes, I hear the same ticking or tapping sound by the fuel filter side upon priming. Car struggles to start & needs foot on the pedal. Once it starts, idles smooth. No CELs. Once turned off & restarted, same struggle as expected from just 8psi of fuel pressure. I extracted the pictured part from a very old Euro-spec 01 R50 filter assembly. One where you need to replace the entire assembly to change the filter...yikes.... Swapped it in, slight improvement in starting but still struggles. I've searched & have not seen any documented R53 filter side fuel pressure regulator failure.....Am I the 1st, again? Remember, not long ago, we hunted this down together.... http://www.motoringalliance.com/forums/cooper-s/14839-morning-hard-starts-now-1-3k-rpm-hesitation-yoyo-hiccup.html The 1st documented split fuel pump hose. Need your thoughts & help to solve another puzzle....again, guys. Thanks much, M/A. FIX UPDATE: 8/26 Drove GPig yesterday & it stalled on me 5 times. Had to be pushed aside. Had to proceed with the surgery as parts arrived. Removed my old pump.... Swapped my buddy's spare 06/2016 production date VDO pump in.... New left, old right. Car still won't start. NOT THE PUMP!!!!! So, I placed the old pump back in. Removed the clicking Filter Assembly, pic'd on the right, w/ a new OE 1....on the left.... Boom!!!! Car instantly started. Puffed a bit & had a bit of misfire & P0300. Cleared & restarted fine. No more clicking from the filter assembly. Took it for a spin, car pulls w/o hesitation. Old guy is back!!!! This 4.55bar Fuel Pressure Regulator that you can't buy separately was the culprit.... One for the archives. Hope this would help those aging gen1s hunt down fuel distribution issues.