What Causes Diesel Generator Fuel Injector Burning

Fuel injector working principle

 

The injector atomizes the diesel fuel and sprays it into the combustion chamber. The injector consists mainly of the nozzle and nozzle holder. The main parts of fuel injector are as follows:

 

1. Rod type filter

2. Cap nut

3. Compressing spring

4. Compression pin

5. Cap nut for fixed nozzle

6. Nozzle holder

7. Connect hole for fuel delivery

8. Nozzle holder

9. Connect tube for overflow

10. Shim

11. Pin

12. Nozzle bush

 

There is no doubt that fuel injection nozzle burning will definitely influence the normal operation of generator set. If you find the related causes, you can quickly solve the problems.

 

1. Long time idling operation

 

Due to the diesel engine keeps running slowly for a long time, the temperature in the cylinder is low, the fuel combustion is not sufficient, the combustion chamber and fuel injection nozzle are easy to form carbon deposition. So it leads to the deterioration of working conditions for fuel injection nozzle. Especially in winter, it is even more serious under the condition of cold climate. Because the combustion chamber has carbon deposition, heat dissipation is slow, which may cause spray orifice obstruction of the fuel injection nozzle and the oil drip phonomenon may happen. The fuel stays in the nozzle head for a long time, the local high temperature will make the nozzle and thermal insulation jacket burned.

 

2. The fuel is not clean

 

Due to there are small particles of impurities in the fuel,  the needle valve and needle valve body of the fuel injector will wear. It is possible that the needle valve will be stuck in the needle valve body.Because of needle valve lag, the fuel can’t be periodically, quantitatively and quickly sprayed into the combustion chamber, the oil drip phenomenon will appear, which may cause the fuel atomization is not good and the combustion speed is reduced. Due to the burning time of the nozzle is extended, which will make the fuel injection nozzle and the thermal insulation jacket burned. When such fault occurs, there will be black smoke and chattering phenomenon.   

 

3. Fuel injection time is too late

 

The fuel injection advance angle is too small which may cause the fuel injection time is too late. If it can’t be adjusted for a long time, the local high temperature will make the fuel injection nozzle and thermal insulation jacket burned.

 

4. Improper assembly

 

If the nozzle insulation sheath is installed without cleaning, there will be a gap between the fuel injection nozzle and the insulation sheath. The gas enters into the gap, the heat insulation and cooling effect is reduced, which will cause the fuel injection nozzle and the insulation sheath burned. If the thermal insulation sheath is too tight, the nozzle will generate additional stress. Under the combined action of heat alternating load and high pressure of fuel injection, the nozzle will be broken and the needle valve will be stuck. In addition, if the insulation sheath can’t get installed during maintenance, the nozzle extends into the combustion chamber more than 4mm above the cylinder head bottom, the heat absorbed by the fuel injection nozzle will increase, which make the nozzle melted.

 

5. Improper use of generator set

 

If it lacks of coolant liquid while the diesel generator set is at work, the combustion chamber can’t be in good state of cooling, which will lead to the high temperature. This is also an important reason to cause the burning of fuel injection nozzle.

 

Prevention

 

As mentioned above, the fuel injection nozzle is one of the important equipment of diesel genset. For the nozzle maintenance, it is necessary to keep the fuel system clean and avoid purchasing the fuel from unreliable sources.