In the Lucas system, fuel from the tank is pumped at high pressure to a fuel accumulator. From there it passes into the fuel distributor, which sends a burst of fuel to each injector, from where it is fired into the inlet port.
The airflow is controlled by a flap valve which opens in response to the accelerator pedal. As the airflow increases, the fuel distributor automatically increases the flow of fuel to the injectors to keep the fuel/air mixture correctly balanced.
For cold starting, a choke on the dash or, on later models, a microprocessor control unit brings a special cold-start injector into operation, which injects extra fuel to create a richer mixture. Once the engine has warmed up to a certain temperature, a thermoswitch automatically cuts off the cold-start injector.