Originally Posted by RES

Can anyone explain to me how the fuel system works? I know there is a FP relay that turns the pump on and there is a Fuel Pressure Regulator that keeps the pressure constant for the injectors. It was mentioned that the pump only stays on for a few seconds when you turn the ignition on and goes back on during cranking and thereafter. I would assume that the Engine Management system tells the pump to turn off after a few seconds. I also assume that the Fuel cutoff valve in not in the loop and is only there for emergencies.