I have now got to the bottom of this problem!
If you undo the four bolts and remove the fuel Cap assembly and turn it upside down, you will see a red plastic valve that is held into the cap by two screws. You will also see three holes in the tank, one is to the overflow pipe, one is the pipe to the canister filter and the other is just a hole that links to one side of the plastic valve, to allow the release of pressure in the fuel tank (when the cap is closed). Originally, the red plastic valve had either a ball or flap (depends on age of bike) to stop fuel leaking into the valve (and running down into the canister and then out onto the exhaust!), when the bike was lent over on track, on long right handed corners.
The problem is that the fuel cap recall, removed the ball bearing, so now even with a fuel level well below the filler neck, with the bike is leaned over on long right handed bends, there is nothing to stop the fuel going into the red plastic valve and then out the other side and down into the top of the canister!
My dealer completely agrees with this analysis and is currently in discussion with Ducati UK.
If someone can tell me how to add pictures, I will do so.
In addition, if the ball in the valve has been removed and you have also removed the canister filter, you have to decide what to do with the canister outlet pipe from the underside of the tank as it will leak fuel when leant over on the track and if you seal it, it will pressurise the fuel tank! The ‘breather’ pipe is not a breather, it’s an overflow pipe for when filling the tank and it does not do anything once you have closed the cap!
Sorry for the long post, but hope it helps.
