publication_number US 2014076281 A1 abstract a low pressure circuit for a fuel injection system such as a common rail injection system includes a predelivery pump by means of which fuel can be drawn out of the fuel tank and supplied via a fuel line to a low pressure region of a high pressure pump a metering unit for flow rate regulation is located in the low pressure region a zero delivery line with a zero delivery throttle branches off downstream of the metering unit and an overflow line with an overflow valve branches off upstream of the metering unit there is located in the zero delivery line a shut off element which can be switched between an open position and a closed position for the selective opening or blocking of the zero delivery line application_number US 201314028094 A description fig1 illustrates a conventional embodiment of a low pressure circuit of a common rail injection system in the standard design the high pressure pump 1 has fitted thereon a mechanical low pressure predelivery pump 2 which is for example in the form of an external gear pump or internal gear pump and which is driven by the camshaft of the high pressure pump and accordingly rotates at the same rotational speed the predelivery pump 2 draws the fuel out of the tank 4 via a pre filter 3 with integrated water separator and delivers said fuel via the main filter 5 to the low pressure region of the high pressure pump 1 the delivery flow rate of the predelivery pump 2 is conventionally configured to be higher than the maximum delivery flow rate of the high pressure pump 1 so as to ensure an adequate charging flow rate to.