Abstract: The fuel feed device comprises a butterfly valve actuated by the driver and an auxiliary throttle member which opens automatically in proportion to the rate of air-flow in the intake passage of the engine. The pressure of the fuel which is delivered into the intake at a location downstream of the butterfly by an injector is adjusted by an unloading valve. The fuel pressure tends to open the unloading valve and the under-pressure which prevails in a control chamber tends to close it. The control chamber has a connection with a portion of the intake which is located downstream of the auxiliary throttle member. That connection is open when the under-pressure is moderate. The connection has also a branch connected to an additional air channel for cold running of the engine which is open when the temperature of the engine is lower than a predetermined value.

Abstract: A carburetor has a main throttle and an auxiliary throttle which is automatically opened in proportion to the air flow in the induction pipe. Fuel is delivered to the induction pipe through a passage whose cross-section is metered in accordance with the position of the auxiliary throttle. The richness of the air-fuel mixture is automatically adjusted by a system comprising a probe which is sensitive to the conditions prevailing in the exhaust pipe. The system periodically opens an air path to the fuel passage and the duration of each opening period is automatically determined for a correct richness to be achieved.

Abstract: The carburetor has a principal fuel jetting system which is situated upstream of a principal throttle member actuated by the operator and, for cold starting, an auxiliary starting device, controlled by the engine temperature, to increase the flow-rate of fuel and if necessary the flow-rate of air admitted into the intake pipe of the engine with respect to the flow-rate corresponding to hot idling. The starting device comprises a closure valve means adapted, as long as the engine has not reached its normal operating temperature, to open a channel which receives a mixture of air and of fuel in a well-determined proportion and which opens into the zone of the intake pipe situated downstream of its principal throttle member. A starting valve situated in the intake pipe upstream of the principal jetting system, is maintained sufficiently open, when the engine is warm, not to substantially enrich the air/fuel mixture on idling and at very small engine loads.