How does the fuel leveling system work on a quattro?

[Diggy98]

Hello guys, I read somewhere that quattro cars have the fuel tank split by the drive shaft and they have some leveling system that keeps the same amount of fuel in both sides. I'm asking this because my car seems to run good only when the fuel level is above half a tank and I think it may have something to do with this leveling thing...is there a pump in the tank doing this job or how does it work more precisely?