Thats the breather pipe. There isn't a hose on it. Mine had the same fault, It's leaking from inside the tank. If you take the filler cap assembly off and look in you'll see a moulded pipe going down the inside of the tank. That gets a hairline crack in it and when the fuel pressurises in the tank it forces it out there. I tired to seal mine from the inside but ended up just removing the tank breather and fitting a race filler cap and letting it vent out the overflow drain on the front left. Blocked the hole up from the top and bottom. Think a few guys have managed to seal it from the inside with epoxy resin though.
