A fuel supply pump supplies fuel from a fuel reservoir to a fuel injection pump which comprises a piston for injecting fuel from a fuel injection nozzle into an internal combustion engine. The piston is reciprocated for fuel injection by an engine driven rotary cam. The fuel injection pump further comprises a fuel control sleeve which is positioned by flyweights to control the fuel injection volume in accordance with the engine speed. A modulator valve is actuated by the flyweights to control the supply pump pressure in accordance with engine speed. A fuel injection timing means is responsive to the modulated supply pump pressure to control the angular relationship between the engine crankshaft and the rotary cam and thereby the fuel injection timing in accordance with the modulated pressure.