My 996 lives in the House Doesnt take up too much space and makes a good clothes horse!! However it makes a very anoying intermitant humming noise that come from the filler cap. Its quite loud Any ideas???
It's depressurising - the pump creates a vacuum in the tank and it has a valve in there somewhere to stop it from imploding due to differences in pressure.
You can sometimes stop it by simply opening up the filler cap and closing it again.