But if it clips on securely then is very probably a damaged or worn O ring in the fuel port of the connector.
the O rings are replaceable, not easily maybe but replaceable. Part #20 in this diagram
I agree with LS avoid cheap connectors also be aware that several makes look the same but are not. Its possible that yours is the same as Yamaha one but they are ever so slightly different to Evinrude ones ( I discovered)