Cause Analysis and Solution of Diesel Generator Injector Failure

Jul. 30, 2021

Diesel engine fuel injector is installed on the cylinder head, the function is the diesel fuel in the form of a finer atomized particles into the combustion chamber and air mixture, forming good diesel engine combustion chamber nozzle, long-term work in high temperature and high pressure and gas corrosion environment, the internal high speed flow of the moving parts of tiny mechanical impurities in the fuel and fuel repeatedly washed. It is easy to wear and corrosion and is one of the most faulty parts in diesel engine fuel system. Today, Dingbo Electric Power, the generator manufacturer , will introduce to you the cause analysis and solution of diesel injector failure.


1.Poor atomization of fuel injector.

When the injection pressure is too low, the jet hole wear has carbon, spring end wear or elastic decline will cause the injector to open in advance, delay closing, and form the phenomenon of bad spray atomization.If the single cylinder diesel engine can not work; If the multi-cylinder diesel engine power drops, the exhaust fumes, the machine running sound is not normal. In addition, because the diesel droplet with too large particle size cannot be fully burned, it flows into the oil pan along the cylinder wall, which increases the oil level, reduces the viscosity, deteriorates the lubrication, and may cause the accident of burning the walla cylinder.

Solution: the injector should be dismantled cleaning, maintenance, re-debugging.


2.Fuel injector return line damaged.

When the needle valve is badly worn or the needle valve body is not closely matched with the injector shell, the oil return of the injector is significantly increased, some up to 0.1 ~ 0.3kg/h. If the return oil pipe is damaged or leaked, the return oil will be lost in vain, resulting in waste.

Therefore, the return pipe must be intact and sealed so that the return oil can flow smoothly into the tank. If the return pipe is connected to the diesel filter, its terminal should be set up a one-way valve to prevent the diesel in the filter into the injector.


3.Needle valve orifice enlarged.

Due to the continuous injection and erosion of high pressure oil flow, the nozzle hole of the needle valve will gradually wear large, resulting in the decrease of injection pressure, the injection distance is shortened, the diesel atomization is poor, and the carbon deposit in the cylinder will increase.

Solution: the aperture of the single hole pin injector is generally greater than 1mm, and a steel ball with a diameter of 4 ~ 5mm can be placed at the end of the hole, and gently hammered with a hammer to make the local plastic deformation of the nozzle hole and reduce the aperture. Perforated direct injection injector because of the number of holes, small aperture, they can only use high speed steel grinding punch in the hole end gently knocking, if the debugging is still not qualified, the needle valve should be replaced.

Cause Analysis and Solution of Diesel Generator Injector Failure


4.needle valve bite.

The water or acid in diesel oil will make the needle valve rust and get stuck. After the seal cone of the needle valve is damaged, the combustible gas in the cylinder will also be docked into the fitting surface to form carbon deposit so that the needle valve is killed, and the injector will lose its injection effect, resulting in the cylinder to stop working.

Solution: the needle valve can be couple in the used oil heated to boiling in the smoke, then remove and use pad with a soft cloth hand vice clamp needle tail slowly, it drew on clean oil, let the needle valve in the valve body activity grinding repeatedly, until the needle valve can couple the horse hour hand valve from the valve body to slowly withdraw from. If the injector test is not qualified, the needle valve should be replaced.


5.Wear on end face of needle body.

The end of the needle valve body end face by the frequent reciprocating movement of the needle valve impact, a long time will gradually form a pit, thereby increasing the needle valve lift, and affect the normal operation of the injector.

Solution: the needle body can be clipped to the grinder to grind this end face, and then grind with fine grinding paste on the glass plate.


6.Fuel injector and cylinder head joint hole leakage oil channeling.

When the fuel injector is installed with the cylinder head, the carbon deposit in the installation hole should be carefully removed. The copper gasket must be flat, and the asbestos plate or other materials shall not be used to replace it, in order to prevent poor heat dissipation or the sealing effect.

If the copper washer is made, it must be processed with copper according to the specified thickness to ensure that the distance of the injector extending out of the cylinder head plane meets the technical requirements. In addition, the injector pressure plate concave should be installed downward, tighten avoid unilateral bias, it should be tightened according to the specified torque evenly, otherwise the injector head will be due to deformation deflection and produce gas channeling oil.


7.Needle valve and needle hole guide face wear.

The frequent reciprocating motion of the needle valve in the needle valve hole, coupled with the invasion of impurities and dirt in diesel oil, it will make the guide surface of the needle valve hole gradually wear so that the gap increases or there are scratches, resulting in the increase in the leakage of the injector, the pressure is reduced, the amount of fuel injection is reduced, the injection time lag, resulting in the start of the diesel engine is difficult.


Solution: When the injection time delay is too much, the locomotive can not even run, at this time should replace the needle valve couple.


8.Droplets of oil appear in the injector.

When the injector is working, the sealing cone of the needle valve body will be subjected to the frequent strong impact of the needle valve, coupled with the high pressure oil flow constantly from the injection out, the cone will gradually appear nicks or spots, thus losing the seal, resulting in oil droplets of the injector.


When the temperature of the diesel engine is low, the exhaust pipe emits white smoke, the engine temperature rises and then becomes black smoke, and the exhaust pipe will emit irregular gun sound. At this point, if the oil supply to the cylinder is stopped, the sound of smoke extraction and firing will disappear.


Solution: the injector can be disassembled, in the needle valve head with a little chromium oxide fine grinding paste (pay attention not to stick in the needle valve hole) to grind the cone, and then clean with diesel oil, into the injector test. If still unqualified, need to replace the needle valve accessories.


If you are interested in diesel generators, please contact us by email We will provide the most considerate service.


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