Swift 2010 fuel system
 

I have a Swift petrol and the manual says that the fuel operates for 2 seconds and stops. I have a problem with the ca and would like to know how the system decides to operate to pump more fuel. There is no regulator on the fuel rail and no return line. If I remove the pipe, with the ignition turned on, it pumps for a couple of seconds and stops. I would have thought that it would have kept on pumping as there is no pressure in the system. Does the engine have to be running for it to operate? How do I test the system? Thanks