How to check the fuel injector

How to check the inspection method and function of the fuel injector?

Fuel injectors are an important part of engine oil supply. The fuel injector receives the fuel injection pulse signal from the electronic control unit to precisely control the fuel injection quantity. Therefore, it is particularly important to detect whether the injector is normal. Let's take a look at the inspection method of the injector and its function.
1. Increase the oil pressure: Increase the injection pressure to 10~20 MPa.
2. Control the injection time: inject and stop the injection according to the specified time.
3. Control the fuel injection quantity: According to the working conditions of the diesel engine, change the fuel injection quantity to adjust the speed and power of the diesel engine.

Type and structure of injector:
(1) According to the structure of the fuel injection port, it can be divided into pin type and hole type.
(2) According to the coil resistance value: high resistance and low resistance
(3) According to the application: MPI, SPI6
(4) According to fuel position: upper fuel supply type and side fuel supply type

Fuel injection process:
(1) The fuel injector is equivalent to a solenoid valve.
(2) When energized, the electromagnetic coil generates electromagnetic force, the armature and the needle valve are sucked up, the fuel injector is opened, and gasoline is sprayed into the air inlet or pipeline through the fuel injection hole.
(3) When the power is off, the electromagnetic force disappears, the armature and the needle valve seal the nozzle hole under the action of the return spring, and the injector stops injecting fuel.
(4) The power on and off of the fuel injector is controlled by the electronic control unit with electric pulses.
(5) The fuel injection quantity is determined by the width of the electrical pulse, pulse width = fuel injection duration = fuel injection quantity
(6) The lift of the needle valve is generally about 0.1mm, and the duration of the fuel injection is in the range of 2~10ms.

How to check the fuel injector
1. When the starter drives the engine to rotate, use a long-handled screwdriver or a stethoscope to listen to whether there is a "click, click" working sound from the injector. If it is difficult to judge due to the influence of other noises, you can use the method of unplugging the injector harness plug to identify whether the injector is working while auscultating.
2. If the injector does not work, connect the test light to the injector harness connector before starting the engine. If the test light flashes, it means that the fuel injector control system is working normally, and the fault lies in the fuel injector. To check the injectors, use a multimeter to measure the resistance of their solenoid coils. If the resistance value is normal, it means that the injector is blocked (affected by carbon deposits and gums in the fuel during combustion). This phenomenon is the most common, the fuel injector should be overhauled, cleaned or replaced, if the resistance value is abnormal, the fuel injector must be replaced.
3. If the test light is off, it means that there is a problem with the control system or circuit of the injector. In this regard, first check whether the related circuit of the fuel injector is intact. Only when the external circuit is intact can it be judged that the computer is faulty.
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