Method for detecting leakage in a fuel rail

A method and apparatus are disclosed for detecting leakage in the fuel supply to the injectors of an engine 10 in which the individual injectors are connected to a fuel supply rail 20 to which fuel from a reservoir 14 is supplied under pressure by a fuel pump 12. The pressure within the fuel rail is monitored and it is determined when a parameter of a pressure surge in the fuel supply rail resulting from a rapid transition from high to low engine load fails to reach a reference value.