FUEL SUPPLY SYSTEM WITH PUMP WITH IMPROVED SEALING PROPERTIES

A fuel supply system comprising a fuel pump (40) for pumping a gaseous fuel to a fuel valve, a source for pressurized fuel (60) and a source of pressurized sealing liquid (57). The fuel pump has a housing with a first bore (84) and a second bore (81). A hydraulically driven actuation piston (83) is slidably received in the first bore (84) and configured to be movable between a retracted position and an extended position. A drive plunger (80) is operably connected to the actuation piston (83) to move in unison with the actuation piston (83). The drive plunger (80) is slidably received with a first clearance (91) in the second bore (81). A pump plunger (87) is slidably received with a second clearance (92) in the second bore (81) and configured to be movable between a retracted position and an extended position. A sealing liquid chamber (86) is arranged in the second bore (81) between a distal side of the drive plunger (80) and a proximal side of the pump plunger (87). A sealing liquid port (70) is connected to the source of pressurized sealing liquid (57), a sealing liquid supply channel (93) fluidically connects the sealing liquid chamber (86) to the sealing liquid supply port (70) when the actuation piston (83) in its retracted position.A pump chamber (82) is arranged in the second bore (81) on a distal side of the pump plunger (87) . A fuel inlet port is connected to the source of pressurized fuel (60), and a fuel supply channel connecting the fuel inlet port to the pump chamber (82).