What are the main manifestations of common fuel injector failures?
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The fuel injector is a key part of the diesel engine, and its working quality directly affects the power, economy, emission and reliability of the diesel engine. According to the requirements of mixture formation and combustion, the injector should have a certain injection pressure, injection stroke and appropriate injection cone angle. In addition, the fuel injector should be able to cut off the fuel supply quickly when the fuel injection needs to be stopped, so that no oil dripping will occur.
Among them, the common injector faults mainly include:
Poor atomization of fuel injector
Symptoms of failure: The power of the diesel engine drops, the exhaust emits black smoke, and the sound of the machine is not normal.
Fault analysis: When the fuel injection pressure is too low, the nozzle hole wears and has carbon deposits, the end face of the spring wears or the elastic force decreases, the fuel injector will open early and close late, and cause poor atomization of fuel injection. In addition, because the diesel mist with too large particle size cannot be fully burned, it will flow into the oil pan along the cylinder wall, which will increase the oil level of the engine oil, decrease the viscosity, deteriorate the lubrication, and may cause an accident of burning the cylinder.
Needle valve stuck
Symptoms of failure: The engine power drops, shakes, and even fails to start.
Fault Analysis: Moisture or acidic substances in diesel oil will cause the needle valve to corrode and get stuck. After the needle valve sealing cone surface is damaged, the combustible gas in the cylinder will also rush into the matching surface to form carbon deposits, causing the needle valve to bite to death. The fuel injector loses its fuel injection effect, causing the cylinder to stop working.
Needle valve and needle hole guide surface wear
Symptoms of failure: The power is reduced, the engine is difficult to start, or even unable to start.
Fault Analysis: The frequent reciprocating movement of the needle valve in the needle valve hole, coupled with the intrusion of impurities in the diesel oil, will gradually wear the guide surface of the needle valve hole. As a result, the gap increases or scratch marks appear, resulting in increased internal leakage of the injector, reduced pressure, reduced fuel injection volume, and delayed fuel injection time, resulting in difficulty in starting the diesel engine. When the fuel injection time is delayed too much, the diesel engine cannot even run, and the needle valve coupling should be replaced at this time.
Injector dripping oil
Fault phenomenon: When the temperature of the diesel engine is low, it is difficult to start, and the exhaust pipe emits white smoke, and when the temperature of the diesel engine rises, it turns into black smoke. And high fuel consumption.
Fault analysis: When the injector is working, the sealing cone surface of the needle valve body will be frequently and strongly impacted by the needle valve. Coupled with the constant injection of high-pressure fuel from there, the tapered surface will gradually become worn or spotted, causing the injector to drip. When the temperature of the diesel engine is low, the exhaust pipe emits white smoke, and when the temperature of the diesel engine rises, it turns into black smoke. Check whether the movement of the needle valve is flexible, the conical surface should be free from wear and the sealing performance should be intact, otherwise, it is necessary to replace the nozzle assembly with a new one.
Oil return is too high
Fault phenomenon: The fuel injection pressure is reduced, the fuel injection time is delayed, and the engine power is reduced, which even causes the diesel engine to stall.
Fault Analysis: When the needle valve coupling is severely worn or the needle valve body and the injector housing are not tightly matched, the oil return volume of the injector will increase significantly. At the same time, it is also necessary to pay attention to the valve plate. Once it is worn out, it will cause excessive oil return from the injector and affect engine performance.
In order to avoid abnormal damage to the injector, it is necessary to change the oil according to the season and maintain the diesel filter regularly. Avoid low-quality fuel and low-quality filters, and avoid long-term high-load operation of the engine. At the same time, it should be pointed out that the common rail system is a dry high-pressure system, please do not disassemble it without authorization to avoid injury. The fuel injector is a precision component, please choose a professional maintenance point for maintenance. Do not disassemble without authorization to avoid secondary damage to the injector.
Among them, the common injector faults mainly include:
Poor atomization of fuel injector
Symptoms of failure: The power of the diesel engine drops, the exhaust emits black smoke, and the sound of the machine is not normal.
Fault analysis: When the fuel injection pressure is too low, the nozzle hole wears and has carbon deposits, the end face of the spring wears or the elastic force decreases, the fuel injector will open early and close late, and cause poor atomization of fuel injection. In addition, because the diesel mist with too large particle size cannot be fully burned, it will flow into the oil pan along the cylinder wall, which will increase the oil level of the engine oil, decrease the viscosity, deteriorate the lubrication, and may cause an accident of burning the cylinder.
Needle valve stuck
Symptoms of failure: The engine power drops, shakes, and even fails to start.
Fault Analysis: Moisture or acidic substances in diesel oil will cause the needle valve to corrode and get stuck. After the needle valve sealing cone surface is damaged, the combustible gas in the cylinder will also rush into the matching surface to form carbon deposits, causing the needle valve to bite to death. The fuel injector loses its fuel injection effect, causing the cylinder to stop working.
Needle valve and needle hole guide surface wear
Symptoms of failure: The power is reduced, the engine is difficult to start, or even unable to start.
Fault Analysis: The frequent reciprocating movement of the needle valve in the needle valve hole, coupled with the intrusion of impurities in the diesel oil, will gradually wear the guide surface of the needle valve hole. As a result, the gap increases or scratch marks appear, resulting in increased internal leakage of the injector, reduced pressure, reduced fuel injection volume, and delayed fuel injection time, resulting in difficulty in starting the diesel engine. When the fuel injection time is delayed too much, the diesel engine cannot even run, and the needle valve coupling should be replaced at this time.
Injector dripping oil
Fault phenomenon: When the temperature of the diesel engine is low, it is difficult to start, and the exhaust pipe emits white smoke, and when the temperature of the diesel engine rises, it turns into black smoke. And high fuel consumption.
Fault analysis: When the injector is working, the sealing cone surface of the needle valve body will be frequently and strongly impacted by the needle valve. Coupled with the constant injection of high-pressure fuel from there, the tapered surface will gradually become worn or spotted, causing the injector to drip. When the temperature of the diesel engine is low, the exhaust pipe emits white smoke, and when the temperature of the diesel engine rises, it turns into black smoke. Check whether the movement of the needle valve is flexible, the conical surface should be free from wear and the sealing performance should be intact, otherwise, it is necessary to replace the nozzle assembly with a new one.
Oil return is too high
Fault phenomenon: The fuel injection pressure is reduced, the fuel injection time is delayed, and the engine power is reduced, which even causes the diesel engine to stall.
Fault Analysis: When the needle valve coupling is severely worn or the needle valve body and the injector housing are not tightly matched, the oil return volume of the injector will increase significantly. At the same time, it is also necessary to pay attention to the valve plate. Once it is worn out, it will cause excessive oil return from the injector and affect engine performance.
In order to avoid abnormal damage to the injector, it is necessary to change the oil according to the season and maintain the diesel filter regularly. Avoid low-quality fuel and low-quality filters, and avoid long-term high-load operation of the engine. At the same time, it should be pointed out that the common rail system is a dry high-pressure system, please do not disassemble it without authorization to avoid injury. The fuel injector is a precision component, please choose a professional maintenance point for maintenance. Do not disassemble without authorization to avoid secondary damage to the injector.