Joely P

Can someone tell me if the fuel pump receives different voltages depending on the state the car is in? My fuel pump isnt priming, i can hear the relay clicking and iv checked the voltage at the pump itself... it gets a prime voltage of between 4v and 8v. This doesnt to move the pump at all.

I have connected the pump direct to a 12v supply and it spins. Im sure i read somewhere that on startup it only receieves 33%... is this controlled by the voltage input?