Engine management system (Fuel system): Description and operation

FUEL SYSTEM

Fuel is drawn from the tank by the injection pump via a filter which removes particle contamination from the fuel.

The injection pump meters a precisely timed, exact quantity of fuel to the injectors in response to throttle variations, injection timing varying with engine speed. Any excess fuel delivered to the injection

Fuel injection pump

pump is not injected, but passed back to the tank via the fuel return line.

Fuel is injected in a finely atomised form into a pre-combustion chamber in the cylinder head where it ignites. The burning fuel expands rapidly into the main combustion chamber, creating extreme turbulence which mixes the burning fuel thoroughly with the compressed air, providing complete combustion.

1. Fuel quantity servo potentiometer
2. Fuel quantity servo control unit
3. Fuel shut off solenoid
4. Injection timing device solenoid valve

The fuel injection pump is a vane-type pump, which is belt driven from the rear end of the camshaft. Fuel delivery from the pump to the injectors is regulated by the movement of a control spool. Movement of the control spool increases or decreases the fuel delivery rate to meet engine operating requirements.

5. Control spool
6. Injection timing device
7. Injection pump drive shaft
8. Fuel temperature sensor

The pump houses the following components which either provide feed back to the engine control module or are controlled by the engine control module: