Get a small #6 or equivalent self tapping screw (like a sheet metal screw) and a drill bit that is equal to the "root" diameter of the threads.
Drill a small hole through the cap only. Be careful, the cap is only ~2mm thick and the head of the fuel screw is right below it - if you go through the cap, it's easy to ruin the head of the fuel screw!
After you drill the small hole, thread the tapered profile screw into the cap until it catches.
Gently twist the screw with pliers while pulling and the plug will come out.