Abstract: A combined accelerator pump and cold start fuel/air mixture supply device has an automatic throttle valve in a mixture supply passage, a fuel control valve controlling flow of fuel drawn into the passage through an inlet upstream of the throttle valve, and an air valve upstream of the fuel inlet. A primary spring tends to seat the air valve. A light, secondary spring urges a plunger against the air valve to augment the load of the primary spring for a predetermined time interval after the engine begins to run under its own power. A valve in a pipe opens automatically at the end of the predetermined time interval to apply engine inlet manifold depression to the end of the plunger remote from the air valve and thereby to separate the plunger from the air valve so that only the primary spring acts on the air valve.

Abstract: An automatic cold start fuel supply device for use with constant depression carburetters having a damped air valve, comprises a fuel metering needle movable with engine temperature by a bimetallic element which acts on it indirectly via a rotary member. A spring, which is normally compressed by the action of manifold depression on a diaphragm, is adapted to act when expanded, through the diaphragm and a lever on an arm of the rotary member. The geometry of the lever and the rotary member is such that the rotary member is so positioned by the bimetallic element when the engine is warm that it is not rotated by the load that is applied to its arm by the action of the spring whereas it is so rotated against the action of the bimetallic element when the engine temperature is below the normal running temperature.

Abstract: An acceleration pump used in conjunction with an automatic cold start air-fuel mixture supply device, comprising a suction-operated diaphragm, and pressure regulating valve means controlling the communication of engine suction to such diaphragm, movement of such valve means being controlled both by thermostatic means responsive to engine temperature and by a control beam responsive to diaphragm movement.

Abstract: A manifold depression responsive fuel pump has its fuel outlet connected to an automatic cold start air/fuel mixture supply device, and a movable stop, which limits movement of the pump diaphragm to enlarge the fuel chamber, has its position controlled by the engine temperature responsive thermostatic control mechanism of the cold start device. The pump diaphragm carries a shut-off valve opposite the pump fuel inlet. Fuel is pumped into the cold start device by the pump when the carburetter throttle valve is opened before the engine has warmed up to normal working temperature. The movable stop is moved towards the pump fuel inlet, as the engine warms up, and seats the shut-off valve in that fuel inlet when the engine has warmed up to its normal working temperature so that the pump does not function to pump fuel into the cold start device once the engine has warmed up to its normal working temperature.