An injection system for an internal combustion engine comprises a valve arrangement (26), connected to an inlet (24) to a high pressure pump (8), which regulates the flow of fuel for lubricating and cooling the high pressure pump (8) and bleeds the injection system. The valve arrangement 926) comprises at least one displaceable actuator and a first and second throttle device (30, 32). The actuator (36) is regulated according to a pressure of the fuel flow between a feed supply pump (6) and the high pressure pump (8), such that a first connection to, the high pressure pump (8) is opened, by means of the first throttle device (30), or the feed (24) to the high pressure pump (8) is interrupted, or a second connection to the high pressure pump (8) is opened, by means of the second throttle device (32). The invention further relates to a method of bleeding and/or regulating said injection system.