using variably controlled air pressure, e.g. by modifying the intake air vacuum signal acting on the fuel metering device

Full Title

Low-pressure fuel-injection apparatus > characterised by means for facilitating the starting-up or idling of engines or by means for enriching fuel charge, e.g. below operational temperatures or upon high power demand of engines > having an enrichment mechanism modifying fuel flow to injectors, e.g. by acting on the fuel metering device or on the valves throttling fuel passages to injection nozzles or overflow passages > using variably controlled air pressure, e.g. by modifying the intake air vacuum signal acting on the fuel metering device