Bosch LU Electronic Fuel Injection

Fig. 1 Bosch LU electronic fuel injection system:

The Bosch LU Electronic Fuel Injection system is used on Alliance and Encore with multi-point fuel injection and on Fuego and Sportwagon models with 4-132 engine. The system, Fig. 1, 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 35 psi (2.5 bars) by means of a pressure regulator in fuel line. Duration of injector operation is determined by engine speed and amount of air flow in intake manifold. Engine speed is derived from distributor in the form of RPM and the amount of air flow is determined by a measuring plate in flow meter.

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 time coolant switch. Additional air is supplied to the intake manifold by a supplementary air regulator to insure proper burning or additional fuel during warm-up. The supplementary air regulator is controlled by the temperature of cylinder head to which it is attached and by an integral electrical heater.