An outboard motor comprising: an engine including a fuel injection device ; a fuel tank including an internal space in which a fuel is storable; a fuel pathway connected to the fuel injection device and the fuel tank ; a fuel pump disposed in the fuel pathway , the fuel pump being configured to supply the fuel from the fuel tank to the fuel injection device ; and a controller programmed to control the fuel pump and to determine whether or not a start condition indicating that an air has entered the fuel pathway is satisfied, characterised in that the controller programmed to determine whether or not a start condition 1 is satisfied, the start condition 1 is that an output of the fuel pump has been kept maximum for a predetermined period of time, wherein when the start condition 1 is satisfied, the controller is programmed to execute fuel running-out determining control, in the fuel running-out determining control, the controller is programmed to drive a sub pump , and simultaneously, programmed to determine whether or not a start condition 2 is satisfied, the start condition 2 is that the output of the fuel pump has been kept maximum, wherein when the start condition 2 is satisfied, the controller is programmed to execute a pump limiting control, in the pump limiting control, the controller is programmed to lower un upper limit of the output of the fuel pump , additionally, during the pump limiting control, the controller is programmed to determine whether or not a start condition 3 is satisfied, the start condition 3 is that engine stalling has occurred or that an engine switch is set in an off position, wherein when the start condition 3 is satisfied, the controller is programmed to execute an air releasing control to open the fuel injection device and drive the fuel pump . an engine including a fuel injection device ; a fuel tank including an internal space in which a fuel is storable; a fuel pathway connected to the fuel injection device and the fuel tank ; a fuel pump disposed in the fuel pathway , the fuel pump being configured to supply the fuel from the fuel tank to the fuel injection device ; and a controller programmed to control the fuel pump and to determine whether or not a start condition indicating that an air has entered the fuel pathway is satisfied, characterised in that the controller programmed to determine whether or not a start condition 1 is satisfied, the start condition 1 is that an output of the fuel pump has been kept maximum for a predetermined period of time, wherein when the start condition 1 is satisfied, the controller is programmed to execute fuel running-out determining control, in the fuel running-out determining control, the controller is programmed to drive a sub pump , and simultaneously, programmed to determine whether or not a start condition 2 is satisfied, the start condition 2 is that the output of the fuel pump has been kept maximum, wherein when the start condition 2 is satisfied, the controller is programmed to execute a pump limiting control, in the pump limiting control, the controller is programmed to lower un upper limit of the output of the fuel pump , additionally, during the pump limiting control, the controller is programmed to determine whether or not a start condition 3 is satisfied, the start condition 3 is that engine stalling has occurred or that an engine switch is set in an off position, wherein when the start condition 3 is satisfied, the controller is programmed to execute an air releasing control to open the fuel injection device and drive the fuel pump . <EOS>