No that's the pcv valve diaphragm. The fuel pressure regulator is on or built into the fuel filter back at the tank. IF the regulator is vented you just need to find the hose in the engine compartment and pull that and make sure no fuel is coming out, there is also a short piece of hose right at the regulator that can be rotten I would be a good idea to check but those things are way down on the list. You are saying the fuel smell is coming from the engine bay right? 20 year old Injector O-rings on a cold morning are up higher on the list.

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)