High pressure fuel injection pump

Pump has housing with working chamber, reciprocally moving piston rotatably mounted about its longitudinal axis and at least one inlet opening. Opening in piston casing is connected to working chamber, interacts with inlet opening and is designed so liquid flowing into working chamber can be adjusted to turn the piston, which has radial groove with radial depth of at least one per cent of piston diameter. The pump has a pump housing (2) with a working chamber (3), a reciprocally moving piston (4) rotatably mounted about its longitudinal axis (A) and at least one inlet opening (21). An opening (5) in the piston casing is connected to the working chamber, interacts with the inlet opening and is designed so the liquid flowing into the working chamber can be adjusted to turn the piston. A groove (8) extending along the periphery of the piston has a radial depth amounting to at least one per cent of the piston diameter. Independent claims are also included for the following: the use of the pump for a diesel fuel injection system for a large diesel engine and a large diesel engine with a drainage coil pump.