Fuel systems for internal combustion engines

A fuel system for a multi-cylinder internal combustion engine comprising a plurality of injection nozzles which in use are mounted on an engine to direct fuel into respective combustion spaces of the engine, each nozzle incorporating a resiliently loaded valve member which controls the flow of fuel through an outlet from a fuel inlet, the valve member being operable by fuel under pressure supplied to the inlet, a fuel pump for supplying fuel to the inlets in turn, pilot pumps incorporated in the nozzles respectively and which when actuated cause a small volume of fuel to be delivered through the respective outlets in advance of the main volume of fuel, pilot inlets on the injection nozzles respectively, said pilot inlets, in use, receiving liquid under pressure in turn to actuate the respective pilot pumps, each nozzle incorporating a non-return valve disposed to allow fuel which has leaked past the respective valve member to flow to the respective pilot inlet when the liquid pressure at the pilot inlet is sufficiently low, the system including a pressure pump for supplying liquid under pressure to the pilot inlets in turn and means for connecting the pilot inlets to a drain during at least part of the time when liquid is not being delivered thereto whereby the fuel which has leaked past the valve member can flow by way of said non-return valve to the drain.