The "intermittent" nature is likely due to the time it takes for sufficient air quantities to be drawn into critical parts of the fuel system, namely high-pressure valves which exist both in the pump and in the injector bodies themselves.
As air is compressible, the valves stop functioning and fuel delivery is halted. With the engine and fuel stopped, any trapped air is free to rise and bleed itself out of the pump, all ready for the next restart.