Group 23 Fuel System
Design and Operation
Injection phase The injection phase begins when the fuel valve (1) closes. The cam on the camshaft continues to press the piston (2) down via the rocker arm and injection takes place as the passage through the fuel valve is closed. The injection phase continues as long as the fuel valve (1) is closed.
1 Fuel valve 2 Pump piston
Pressure release phase Injection stops when the fuel valve opens and the pressure in the injector falls below the opening pressure of the atomizer. The fuel flows through the open valve, through the injector hole and out through the fuel passage. Note that it is the position of the fuel valve (closed or open) which determines when injection begins and ends. The duration for which the fuel valve is closed determines the quantity of fuel injected on each pump stroke.
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