- Fuel Valve is also called the fuel Injector. It is fitted on cylinder head, which encompasses the combustion chamber. A fuel valve consists of a valve body or nozzle holder to which the nozzle is secured by a retaining nut. There is a spring and its compression nut within the valve body, along with an intermediate spindle if necessary. Mating surfaces between valve body and nozzle are ground and lapped to form an oil pressure-tight seal.
2. The fuel injection pump delivers high-pressure fuel to the fuel valve through high-pressure fuel pipe. The injector is mounted on the cylinder head by the integral flange in the holder and two studs with distance pieces and nuts.
3. Fuel valve operates hydraulically lifting a spring-loaded valve allowing the pressurised fuel to spray out through one or more orifices into the combustion chamber. The functions of a fuel injector are:
- Open and close the passage of fuel to the combustion chamber
- Convert the high-pressure oil from the pump into a fine spray of desired pattern
4. The nozzle and needle are lapped together as a pair and cannot be replaced individually. The nozzle holder includes a threaded pipe stub for mounting the high-pressure pipe. On the uppermost part of the nozzle holder, there are three sealing rings. Between the two lowest O rings, the leak-off oil from the fuel valve is led out in to the spacing between the high-pressure piping and the protection tubing. The nozzle assembly and the fuel valve are cooled by the injected fuel.
When removing fuel injectors it is important to number the injector, there should be an record for the injectors, parts changed and serial numbers. All parts should be tracked.
