Author:Site Editor Publish Time: 2020-12-25 Origin:Site
The automobile fuel metering unit is installed in the high-pressure fuel pump, and all diesel fuel passes through it, and then through the common rail to the fuel injector.
Two pipes When you don’t know which is the inlet pipe and which is the outlet pipe, how can we tell? Because they all look the same. So we can look at a pipe, and if the end of the pipe is connected to the injector, it is the oil inlet pipe. The other end is connected to the pressure valve.
The automobile pressure limiter valve and its working principle are simply to control the oil intake and return through the pressure value. The oil pump first draws oil from the oil tank. Then it passes through the fuel inlet pipe, then through the fuel pressure regulator, the fuel returns to the return pipe, and finally flows back into the fuel tank. The pressure regulator regulates the oil pressure. When the oil pressure is too high, the valve will open to let the oil return to the tank and reduce the oil pressure. When the oil pressure is too low, the valve will be closed to increase the oil pressure.
The fuel pressure control valve relies on vacuum pipe suction to open the valve. Therefore, the valve can be opened only when the car is started and the air intake is inhaled.
So sometimes this has a problem, which causes the oil pressure to be too low. It may be difficult to start a cold car. Or poor acceleration because the oil pressure is too low. If the oil is too high, this may damage the oil pump. Then the fuel injector may be damaged. Another hot car may not start well, because if the oil pressure is too high, the oil cannot be returned normally, resulting in oil leakage in the injector. Therefore, if the fuel injection is too large, it is easy to wet the spark plug and affect it not to start.
After the suction control valve is disassembled, it is mainly composed of the following parts. The electromagnetic coil is integrated in the shell. Front iron gasket. case. Piston, spring, adjusting washer.
There are two types of fuel metering units: normally open and normally closed. How to judge whether the fuel metering unit is normally open or normally closed? The simplest and most accurate method is to judge by observing the position of the triangular hole on the piston.
The fuel metering unit piston is the most problematic component. Through the fuel metering unit fork type precision screwdriver. It can quickly and accurately judge the quality of the fuel metering unit piston.
Insert the fuel metering unit fork type precision screwdriver. Rotate the fuel metering unit piston. In the absence of power, observe the position of the triangular hole through the measurement hole. After one rotation, if no triangle hole is found, then the fuel metering unit is a normally closed fuel metering unit. If a triangular hole is found, it means that the fuel metering unit is a normally open fuel metering unit.
Inside the fuel metering unit is a set of coils. This coil of the fuel metering unit is generally difficult to damage, and can be judged by measuring the resistance of the coil resistance. The normal resistance value is between 2.6-3.1.
What is it easy to damage? Generally it is the spool. Long-term wear and tear can easily get stuck. If it is stuck, it is impossible to adjust the oil intake, which will eventually lead to failure.
When the metering unit fails, there may be no problem with the speed, but the common rail pressure is very unstable. The fuel metering unit has been unable to accurately control the pressure. At this time, you need to replace the fuel metering unit.
Another function of the fuel metering unit fork type precision screwdriver is to determine whether the fuel metering unit is stuck. Insert the Fork Type Precision Screwdriver of the fuel metering unit and gently rotate the piston of the fuel metering unit. If it is difficult to rotate or does not move, the fuel metering unit is stuck.
Determine whether the fuel metering unit piston is rusty or worn
Another function of the fuel metering unit fork type precision screwdriver is to determine whether the surface of the fuel metering unit is rusty or worn.
Insert the fuel metering unit fork type precision screwdriver and gently rotate the fuel metering unit piston. Observe whether there is wear or rust on the surface of the piston through the side hole.
The surface of the normal piston is smooth without wear and rust.