81 380SLC stored for the last 5 years. Fuel tank was drained prior to storage by removing the fuel line between tank and fuel pump. When I started the car several hours ago there was a continuous humm coming from the fuel pump like it was running continuously. When you shut off the engine and then turn the switch back on there is no noise. Afraid to go any farther as I don't want to burn out the fuel pump. Could there be air in the system somewhere from the tank draining 5 years age? Thanks, Bob