Fuel supply systems

Claim 1

A fuel supply system for an internal combustion engine having a plurality of cylinders, air supply conduit means and a plurality of main intake tubes connecting the cylinders to the air supply conduit means, said system comprising a respective main injection nozzle positioned to introduce fuel into each intake tube and main air control means operable to regulate air flow from the supply conduit means to the main intake tubes, a secondary, heated, intake tube of relatively small crosssectional area connected to the air supply conduit means, a sole secondary injection nozzle positioned to introduce fuel directly into the heated portion of the secondary intake tube, and secondary air control means operable to regulate air flow from the supply conduit means to the secondary intake tube, the secondary intake tube also being connected to the cylinders to supply heated fuel air mixture thereto, fuel flow control means for controlling the supply of fuel to said main injection nozzles and to said secondary injection nozzle separately, a control mechanism for operating both said air control means and said fuel control means, said control mechanism being connected to operate said fuel flow control means to admit fuel to said secondary injection nozzle only, and to operate said secondary air control means to admit air to the secondary intake tube at a rate which increases with increasing fuel supply to said secondary injection nozzle, at least up to a predetermined point, as said control mechanism is moved through a first operating range, and to then operate said fuel flow control means to initiate fuel supply to said main injection nozzles and operate the main air control means to admit air to the main intake tubes at a rate which increases with increasing fuel supply to said main injection nozzles, as said control mechanism is moved beyond said first operating range.