Bosch L-Jetronic Electronic Fuel Injection

Fig. 1 Bosch L-Jetronic fuel injection system.:

The Bosch L-Jetronic electronic fuel injection system, Fig. 1, is used on Fuego Turbo models. The system relies on engine speed and the amount of air being drawn into the intake manifold for basic operation. Fuel is drawn from the fuel tank and pressurized by an electric pump which then makes the fuel available for injection into the intake ports by the electro-magnetic fuel injectors.

Fuel pressure is limited to 36 psi (2.5 bars) by means of a pressure regulator in the fuel line and is located in the engine compartment. The duration of the injector operation is determined by engine speed and by the air flow in the intake manifold. Engine speed is taken from the distributor in the form of RPM. The amount of air flow is determined by the measuring plate in the flow meter, which is located before the throttle.

During warm up, additional fuel is injected into the intake manifold by a cold start injector. The cold start injector is controlled by a thermal coolant time switch. Also, additional air is provided by the auxiliary air valve to the intake manifold to insure proper burning of the additional fuel during warm-up. The auxiliary air valve is controlled by the engine ambient temperature and by electrical resistance.