Abstract: A fuel system for a gas turbine engine comprising a regenerative pump having an inlet, an outlet, and a flow channel extending between the inlet and the outlet along which fuel is transferred in use by rotation of an impeller of the regenerative pump, a fuel supply line in use supplying fuel at low pressure to said pump inlet, an output line in use receiving fuel at high pressure from said pump outlet for distribution to a gas turbine engine, and, a spill line into which fuel from said pump outlet can be spilled, said spill line being connected to said flow channel of said regenerative pump at a selected point between the inlet and outlet of said pump to discharge spilled fuel in use into said flow channel.