Hello,
I would recommend checking the fuel lines on top of the tank. This is where the sending units are located. The fuel lines can get cracked and seep into pockets on top of the tank. This keeps the fuel from being seen leaking onto the floor.
You can access these by removing the back seat and removing the covers over the tank,one on each side. You may need to replace the fuel lines.
Thanks.
BMW Technician
Master BMW and Master ASE Certified
Hello, you do not need to remove the upper sections of the seat.
Grasp the front edge of the lower cushion and give it a good pull upward.
This is just snapped in on each side.
Then you can lift the lower seat cushion out and access the covers over the tank.
Thanks for the Accept and feel free to respond with any further questions.
--Merry Christmas--