When the igntion is switched on voltage is supplied to the fuel pump.
The Ecu briefly earths the fuel pump relay contact 85 at terminal 28 of the Ecu.
This energises the the relay winding which closes the relay contact and connects voltage from terminal 30 to terminal 87 thereby providing voltage to the fuel pump circuit.
After approx 1 second the Ecu opens the circuit and the pump stops.
This brief running of the fuel pump allows pressure to build within the the fuel pressure lines and provides for an easier start.
The fuel pump circuit will remain open until the engine is cranked or run. One the Ecu receives a speed signal from the CAS the relay winding will again be energised by the Ecu and the fuel pump will run until the engine is stopped.
***Taken from the Weber Marelli Technical Data.***

Just to add, the NRV in the pump is designed to maintain pressure when the engine turns off to enable restarting easier. Perhaps this is where some of you are getting confused.

Hope you get it fixed...........