It is annoying to not being able to click the fuel cap back in place, you need to use the key to open and to close the cap. For people with a Scott Damper in place this is highly annoying as the cap is hinged forward: you need to use the key to open the cap, remove the key so it doesn’t hit the damper, open fully, fill the tank and then put the key back in the lock to close the cap.
An excellent solution is a hack that allows for closing the fuel cap by just pressing on it, no key necessary. The key is still required to open the cap, but you can remove it right away as you don’t need it to close.
First you need to take out the 2 Phillips screws to remove the cover over the latch pawl: watch out the spring and pawl will probably go flying, as they did on this pic. This can be done on the bike, but make sure you cover and protect the hole so nothing can fell in the fuel tank. An alternative is to first remove the assembly from the bike.
When you have retrieved the pawl and spring, take the pawl and mark the black area, which will have to be removed to allow the pawl to move when the key is removed:
Drill, grind, file with your favorite tools (drilling first to the floor, then dremel to finish seems the easiest way to do so) until you get to this result:
You then reassemble the lock by carefully maintaining the spring and pawl in place while you slid and screw the cover back on top.
[This is all a copy of the AdvRonski hard work on AdvRider.com. All credits to him for the idea, the realisation and the photos, all on this post. And to Braaap! who followed the instructions successfully and encouraged me to put this in the FAQ]