Systems and methods for purging a fuel manifold of a gas turbine engine

Fuel systems of gas turbine engines of aircraft, and associated methods are provided. The fuel systems and methods can permit reverse purging of one or more fuel manifolds of a gas turbine engine to prevent coking in some modes of operation. A fuel system includes first and second fuel manifolds fluidly connectable to a combustor of the gas turbine engine. A valve is operatively disposed between the second fuel manifold and a fuel supply line for controlling fuel supply to the second fuel manifold. A reservoir includes a movable piston disposed therein and dividing the reservoir into a first chamber and a second chamber. The first chamber is fluidly connectable to the fuel supply line or to a fuel purge line via the valve. The second chamber is in fluid communication with the second fuel manifold to receive residual fuel from the second fuel manifold.