hello there all of a sudden im hearing what sounds like an electrical short under my tank? its my 2007 sportster its parked, ignition off and i hear this kind of buzzing coming from under the gas tank, top of engine area , ill hear it for a few seconds then it would stop , then a few seconds later there it is again ??? its dark now i looked around best i could , but didnt see anything obvious, any ideas what this might be ????