How to Check the Failure of the Fuel Pressure Regulator

The fuel pressure regulator is a component that guarantees the normal fuel pressure in the automobile oil circuit. There is a diaphragm inside the pressure regulator to control the opening and closing of the pressure valve. When the oil pressure is lower than a certain value, the pressure valve is closed. The pressure of the oil pump increases the pressure in the oil circuit. When the pressure increases to exceed the specified pressure, the diaphragm opens, and the over-pressured fuel flows back to the tank through the oil return line to reduce pressure.

The role of the fuel pressure regulator

The function of the fuel pressure regulator is to adjust the fuel pressure entering the injector according to the change of the intake manifold pressure so that the two maintain a constant pressure difference so that the amount of fuel injected from the injector only depends on At the opening time of the injector. The ECU can precisely control the fuel injection volume by controlling the length of the fuel injection time.

Posted on Jan 29,2021 by Sharon Wen
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Working principle of the fuel pressure regulator

The oil pressure is coordinated by the spring and the vacuum degree of the air chamber. When the oil pressure is higher than the standard value, the high-pressure fuel will push the diaphragm upward, the ball valve will open, and the excess fuel will flow back into the fuel tank through the return pipe; At the standard value, the spring will press down the diaphragm to close the ball valve and stop returning oil. The function of the pressure regulator is to keep the pressure in the oil circuit constant. If the oil pressure is too low, the injector will inject too weakly or not. If the oil pressure is too high, the oil circuit will be damaged or the injector will be damaged.

There is a diaphragm inside the pressure regulator, which plays the role of controlling the opening and closing of the pressure valve. When the oil pressure is lower than a certain value, the pressure valve is closed. The pressure in the oil circuit is increased by the pressure of the oil pump. When it exceeds the specified pressure, The diaphragm opens, and the over-pressured fuel flows back to the fuel tank through the oil return line to reduce pressure.

1 What are the symptoms of a broken fuel pressure regulator:

1. 1 The car is not easy to ignite when the fuel pressure regulator is broken.

When there is a problem with the fuel pressure regulator and the fuel cannot be supplied normally, it is very likely that when we ignite, the power of the car will not meet the requirements and it is difficult to start.

1.2 The fuel pressure regulator is broken and the gasoline is polluted.

If the fuel pressure regulator has a problem caused by the ingress of mixed air, it may cause our gasoline to be contaminated by the mixed air, causing the gasoline to not be used normally.

2. How to check the fuel pressure regulator

2.1 Check the working conditions of the fuel pressure regulator:

The inspection method is: use an oil pressure gauge to measure the gasoline pressure when the engine is idling, then unplug the vacuum hose on the gasoline pressure regulator and check the gasoline pressure. At this time, the gasoline pressure should increase by about 50kPa. If the pressure change does not meet the requirements, the gasoline pressure regulator is not working properly and should be replaced.

2.2 Check the fuel pressure regulator to maintain pressure:

This inspection should be done when the maintenance pressure of the fuel system does not meet the standard value (below 147kPa). The inspection method is: connect the oil pressure gauge to the fuel pipeline and use a wire to short the two detection jacks of the electric fuel pump. Turn on the ignition switch and let the electric fuel pump run for 10 seconds, then turn off the ignition switch and remove the wire. Then clamp the oil return pipe of the gasoline pressure regulator, and observe the gasoline pressure after 5 seconds. This pressure is the holding pressure of the gasoline pressure regulator. If the pressure is lower than the fuel system holding pressure.

3. What to do if the fuel pressure regulator fails

3.1 Clean the injector, throttle body, and idle speed motor.

If we have a problem with the fuel pressure regulator during driving, we should check if it is caused by the unclean fuel injector, throttle body, and idle motor, and then inspect and clean it.

3.2 Check the vacuum diaphragm.

Inside the fuel pressure regulator, there is a vacuum diaphragm, which is designed to better ensure the normal use of our regulator and prevent gasoline from leaking out. If we find that the fuel pressure regulator is malfunctioning, we can check Whether the vacuum diaphragm is broken.

3. 3 Discharge of mixed air.

The problem with our fuel pressure regulator is often caused by the contamination of the mixed air entering the interior. At this time, we only need to discharge the mixed air and check the airtightness of the regulator.


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