Cold starting devices

A cold start device for an internal combustion engine, the cold start device comprising a body;

• a gas supply passage formed in the body;
• one end of the gas supply passage
• being for connection to the inlet manifold of an internal combustion engine so that gas can be drawn through said gas supply passage by the action of engine suction when the device is installed on an internal combustion engine;
• a valve for controlling gas flow into said gas supply passage;
• means upstream of said gas flow controlling valve for varying the supply of air to said gas supply passage so as to control the depression established within the gas supply passage between said varying means and said valve, means resiliently biassing said varying means to a position of minimum air supply, said biassing means acting in opposition to the effect of a depression established within the gas supply passage between said varying means and said valve to increase the air supplied by said varying means;
• and a fuel valve to control flow of fuel from a fuel supply system to said gas supply passage between said varying means and said valve, said fuel control valve being responsive to a depression in the gas supply passage between said varying means and said valve, wherein the improvement comprises plunger means, at least part of said resilient biassing means acting through said plunger means, means exposing a surface of said plunger means to the pressure at the inlet manifold of an internal combustion engine so that, when the device is installed on an internal combustion engine, the biassing effect of said resilient biassing means upon said air supply varying means is reduced by the thrust due to the action of a depression which is substantially that which is established in the inlet manifold of the engine upon said plunger.