High Pressure (Hp) Fuel Pump And Fuel Injectors
The fuel system is of a common rail design consisting of a high pressure pump, fuel rail and injectors with associated low and high pressure pipes.
The high pressure fuel pump is located at the rear of the engine and is driven by a chain drive from the crankshaft at engine speed. The fuel pump is mounted on the cylinder block and secured with three bolts. The high pressure fuel pump is a single cylinder design which regulates the fuel pressure according to demand requirements for correct fuel injection. The delivery rate of the fuel pump is adjustable by means of a fuel metering valve which is controlled by the PCM. Fuel is used to lubricate the moving components of the pump before being returned to the fuel tank.
High pressure fuel is supplied via a high pressure feed pipe to the fuel rail which is located on the camshaft carrier. The fuel rail is a pressure reservoir which provides the fuel supply to the injectors. The fuel rail also houses a fuel pressure sensor and a fuel pressure control valve. The fuel pressure control valve is utilized by the PCM in conjunction with the fuel pump metering valve to ensure that the correct pressure is maintained within the fuel rail. The PCM software determines which valve, or combination of the two valves, is appropriate to maintain the correct pressure. Excess fuel, bypassed from the pressure control valve operation, is returned to the inlet side of the fuel filter. The raised temperature of this fuel assists with fuel filter heating in cold ambient temperatures.
Pressurized fuel is supplied from the fuel rail via steel pipes to each individual injector. The engine uses solenoid injectors which are mounted centrally in the combustion chamber and retained with clamps. The injector does not inject the entire quantity of fuel it is supplied; a small amount of fuel from the injector is collected by a low pressure injector leak-off pipe and returned to the fuel tank along with the fuel pump's return.
It is important to note that the fuel injector specifications may vary in respect to the power output of the specific engine variant.