They souldn't but they are old now. Squatt down next to the filler cap.
Follow the small bore hoses that run up the fuel inlet. There are two of them, one from the tank to fuel neck and a return which hangs loose over the left hand side of the fuel tank. They break up with age. 6mill pipe i think.
Just stick your hose up the NSF rear wheel arch and you will see them:lmao: