Fuel injector failure how to repair?

Fuel injector failure how to repair?

Abstract: The injector is a precision device with very high processing accuracy, which requires a large dynamic flow range, strong anti-blocking and anti-pollution ability, and good atomization performance. The fuel injector receives the injection pulse signal sent by the ECU, and accurately controls the fuel injection amount. So how to repair the fuel injector if it fails?


Fault symptoms of fuel injector damage:

If the fuel system of the engine is poorly maintained (the injector is cleaned regularly), it may lead to the accumulation of glue inside the injector, rather than the blockage of the valve hole or the stuck needle valve. Clogged injector valve holes can lead to fuel injection failure (complete blockage) or poor atomization (partial blockage). The stuck needle valve will lead to drip after injection, resulting in unstable idle speed, poor acceleration, or difficult starting of the engine, which seriously affects the emission performance of the engine. In addition, the fuel injector connector water will lead to a short circuit, and can not inject fuel, so pay attention to clean maintenance. The engine can not start, the engine operation is unstable, and the exhaust is serious. These are symptoms of a damaged fuel injector.


Main fault types of fuel injectors:

  1. The valve hole is blocked, resulting in no oil injection or poor atomization.
  2. The needle valve is faulty, resulting in flow error or leakage after injection.
  3. Connector break/short circuit prevents fuel injection.


Check the performance of the fuel injector:

  1. Listening to working sound detection: When the engine is running or starting, use a noise stethoscope or similar tools to check the working sound of the injector. The operating sound period of the injectorwill change with the engine speed. If no sound is heard or an abnormal sound is heard, check the injectorcircuit (line or connector) or the injector.
  2. Resistance check: Turn off the ignition switch and disconnect the injectorconnector. Use a multimeter to measure the resistance between the two terminals of the injectorto 12 at 20(68).
  3. Flow and leak check: (1) Assemble the fuel injectorand reversing tool. (2) Install a suitable ethylene pipe on the fuel injectorto prevent fuel overflow. (3) Place the cylinder under the injector. (4) Run the fuel pump to deliver the fuel to the injector. A. Connect the tester to the DLC, perform the "component test" mode, and drive the electric fuel pump. B. Disconnect the connector of the fuel pump relay, short-connect the two terminals of the fuel pump relay with the service wire, and force the electric fuel pump. (5) Apply voltage to the injector with the battery for 15 seconds, measure the amount of fuel injection with the measuring cylinder, and measure each injector 2 to 3 times. The reference value of fuel injection is about 46cc/15s. If the measured value is significantly out of specification, replace the injector. (6) Check the leakage of the injector nozzle. Do not run the nozzle during this inspection (but the fuel pump should work). If the fuel leaks more than 1 drop/minute, replace it.

Fuel injector inspection methods are described as follows:

  1. When the starter drives the engine to rotate, use a long-handled screwdriver or stethoscope to listen to whether the injectorhas a "click, click" working sound. If it is difficult to tell due to other noise, it is possible to identify whether the injectoris working by pulling and inserting the injector harness plug while ausculting.
  2. If the injectoris not working, connect the test light to the harness plug of the injectorbefore starting the engine. If the test light blinks, the injector control system is working properly and the fault is in the injector. When checking the injector, use a multimeter to measure the resistance value of its electromagnetic coil. The resistance value is normal, indicating that the injector is blocked, the needle valve is stuck, etc. The injector should be serviced, cleaned, or replaced; If the resistance value is abnormal, the injector must be replaced.
  3. If the test light is not on, the control system or circuit of the injectoris faulty. In this regard, we must first check whether the relevant circuit of the injectoris intact, and only if the external circuit is intact can we judge that the computer is faulty.

Precautions for syringe maintenance:

  1. Regular use of a special cleaning analyzer to thoroughly clean the injectorcan greatly improve the service life of the injector, so that the power performance, fuel consumption, and emission performance are maintained in good condition.
  2. The top of the injectoradopts a rubber sealing ring and oil rail interface to form a reliable pressure fuel seal, and the lower part also adopts a rubber sealing ring and engine intake manifold to seal the air. These two parts need to be replaced each time the injectoris removed.
  3. When installing the injectoror supply line, first lubricate the O-ring with gasoline.


When the injector is working, the sealing cone of the needle valve body will be subjected to frequent strong impact of the needle valve, coupled with the high-pressure oil flow constantly sprayed out from there, the cone will gradually appear notches or spots, thereby losing the seal and causing the injector to drip oil. When the temperature of the diesel engine is low, the exhaust pipe will emit white smoke, and after the engine temperature rises, it will become black smoke, and the exhaust pipe will emit irregular cannon sounds. At this time, if the oil supply to the cylinder is stopped, the smoke exhaust and the sound of firing will disappear. Maintenance method Disassemble the injector, grind the cone surface with a little chromium oxide fine grinding paste on the head of the needle valve (be careful not to stick in the needle valve hole), and then wash it with diesel oil and put it into the injector for test. If not, replace the needle valve pair.

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