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 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 valve housing for connection to a source of pressurized low flashpoint fuel, an actuation fluid port in said elongated valve housing for connection to a source of actuation fluid, an axially displaceable valve needle slidably received in a longitudinal bore in said fuel valve, said valve needle having a closed position and an open position and said valve needle being biased towards said closed position, said valve needle allowing flow of fuel from a fuel cavity to said plurality of nozzle holes when the valve needle is in its open position and said valve needle preventing flow of fuel from said fuel cavity to said plurality of nozzle holes when the valve needle is in its closed position, 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 fluid port, said pump chamber having an outlet fluidically connected to said fuel cavity and an inlet fluidically 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 for sealing said pump piston in said first bore, a conduit (93,97) connecting said sealing liquid inlet port to said longitudinal bore at a first position along the length of said longitudinal bore for sealing said valve needle in said longitudinal bore, a conduit connecting the low flashpoint fuel inlet port to said longitudinal bore at a second position along the length of said longitudinal bore, said second position being closer to said fuel cavity than said first position. an elongated 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 valve housing for connection to a source of pressurized low flashpoint fuel, an actuation fluid port in said elongated valve housing for connection to a source of actuation fluid, an axially displaceable valve needle slidably received in a longitudinal bore in said fuel valve, said valve needle having a closed position and an open position and said valve needle being biased towards said closed position, said valve needle allowing flow of fuel from a fuel cavity to said plurality of nozzle holes when the valve needle is in its open position and said valve needle preventing flow of fuel from said fuel cavity to said plurality of nozzle holes when the valve needle is in its closed position, 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 fluid port, said pump chamber having an outlet fluidically connected to said fuel cavity and an inlet fluidically 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 for sealing said pump piston in said first bore, a conduit (93,97) connecting said sealing liquid inlet port to said longitudinal bore at a first position along the length of said longitudinal bore for sealing said valve needle in said longitudinal bore, a conduit connecting the low flashpoint fuel inlet port to said longitudinal bore at a second position along the length of said longitudinal bore, said second position being closer to said fuel cavity than said first position.