Their is a T that goes to the Tank and the driver side of the engine which runs to a solenoid in the trunk.
That solenoid then goes to the exhaust flaps.
https://www.realoem.com/bmw/enUS/sho...diagId=11_5038
#6 is a T, which runs to the driver side of engine.
Get a hand held vacuum pump. It will make your search easier.
Also check the check valve on the actual vacuum pump. The diaphragm could have failed.
Where in florida are you?