A fuel valve for injecting low flashpoint liquid fuel into the combustion chamber of a large slow running two-stroke turbocharged self-igniting internal combustion engine, said fuel valve comprising: an elongated fuel valve housing with a rear end and a front end, a nozzle with a plurality of nozzle holes, said nozzle being disposed at the front end of said elongated valve housing, a fuel inlet port in said elongated fuel valve housing for connection to a source of pressurized liquid fuel, an actuation liquid port in said elongated fuel valve housing for connection to a source of actuation fluid, an axially displaceable valve needle slidably received in a longitudinal bore in said elongated valve housing, said valve needle having a closed position and an open position, said valve needle rests on a valve seat in said closed position and said valve needle has lift from said valve seat in said open position and said valve needle being biased towards said closed position, a fuel chamber in said elongated valve housing, said fuel chamber surrounding said valve needle and opening to said valve seat, a pump piston received in a first bore in said valve housing with a pump chamber in said first bore on one side of said pump piston, an actuation piston received in a second bore in said valve housing with an actuation chamber in said second bore on one side of said actuation piston, said pump piston being connected to said actuation piston to move in unison therewith, said actuation chamber being connected to said actuation liquid port, said pump chamber having an outlet connected to said fuel chamber and an inlet connected to said fuel inlet port, a sealing liquid inlet port for connection to a source of pressurized sealing liquid, a conduit connecting said sealing liquid inlet port to said first bore, said conduit opens to the clearance between said first bore and said pump piston for sealing said pump piston in said first bore. an elongated fuel valve housing with a rear end and a front end, a nozzle with a plurality of nozzle holes, said nozzle being disposed at the front end of said elongated valve housing, a fuel inlet port in said elongated fuel valve housing for connection to a source of pressurized liquid fuel, an actuation liquid port in said elongated fuel valve housing for connection to a source of actuation fluid, an axially displaceable valve needle slidably received in a longitudinal bore in said elongated valve housing, said valve needle having a closed position and an open position, said valve needle rests on a valve seat in said closed position and said valve needle has lift from said valve seat in said open position and said valve needle being biased towards said closed position, a fuel chamber in said elongated valve housing, said fuel chamber surrounding said valve needle and opening to said valve seat, a pump piston received in a first bore in said valve housing with a pump chamber in said first bore on one side of said pump piston, an actuation piston received in a second bore in said valve housing with an actuation chamber in said second bore on one side of said actuation piston, said pump piston being connected to said actuation piston to move in unison therewith, said actuation chamber being connected to said actuation liquid port, said pump chamber having an outlet connected to said fuel chamber and an inlet connected to said fuel inlet port, a sealing liquid inlet port for connection to a source of pressurized sealing liquid, a conduit connecting said sealing liquid inlet port to said first bore, said conduit opens to the clearance between said first bore and said pump piston for sealing said pump piston in said first bore.