A fuel injection system for a gas trubine engine combustion chamber comprises at least one pilot fuel injector having a fuel discharge passage communicated to the combustion chamber and at least one secondary fuel injector having a fuel discharge passage communicated to the combustion chamber and a fuel purging passage communicated to a higher pressure region upstream of the combustion chamber. A fuel flow control device supplies metered fuel flow to the pilot fuel injector under all regimes of engine operation and to the secondary fuel injector under certain, intermittent regimes of engine operation requiring fuel flow above a selected level. A shuttle valve is movable to a first position to provide fuel flow communication between the fuel control device and the fuel discharge passage of the secondary fuel injector for fuel injection to the combustion chamber. The shuttle valve also is movable to a second position to communicate the fuel discharge passage and the fuel purging passage of the secondary injector to the higher pressure region to purge fuel from the fuel discharge passage to the combustion chamber.