What is the phenomenon of automobile oil pump damage? Maintenance technician: There are mainly three kinds of failure phenomena.

Automobile fuel pump, also called fuel pump or gasoline pump, is a very important part of the engine fuel system, and its function is to give the fuel system a certain fuel pressure (about 250-300KPa). If the fuel pump is damaged, it will lead to engine starting difficulties, poor acceleration or low operating efficiency. Let's analyze the reasons in detail.

Working principle and structure analysis of gasoline pump

At present, EFI gasoline vehicles basically use electric fuel pumps, although different engines supply oil in different ways. The composition of the fuel system is shown in the following figure, in which the electric fuel pump (gasoline pump) is installed in the automobile fuel tank, which is called built-in. The oil pump can be submerged in the oil tank to prevent gas resistance and air from entering the oil circuit. The pumping capacity of gasoline pump should increase with the increase of engine load and speed. Generally, the maximum pumping oil quantity is more than twice the maximum oil supply required by the engine to meet the maximum engine load.

Compared with the previous mechanical diaphragm oil pump, the electric fuel pump has been greatly improved, which can reduce the internal wear of the oil pump and make its performance more stable. The intake of diaphragm gasoline pump is driven by the eccentric wheel of engine camshaft. The eccentric wheel drives the diaphragm pull rod to move down through the rocker arm, compressing the diaphragm spring, increasing the volume on the diaphragm and generating a certain degree of vacuum suction.

The structure of electric fuel pump is shown in the following figure. As can be seen from the figure, it is mainly composed of shell, armature (rotor), upper and lower end covers, magnet and impeller. When the plug of the oil pump is energized (for example, under the starting condition), the armature of the permanent magnet motor will be energized and the fuel will be sucked out of the bottom filter.

The end of the armature is connected with an impeller, and the edge of the impeller has many tooth gaps, and both sides of the inner shell are provided with an oil inlet and an oil outlet. Under the action of the impeller, the fuel enters the oil pump from the oil inlet and flows out from the oil filler after being pressurized. Because as long as the oil pump works, the fuel will continuously cool the armature rotor running at high speed, so no matter how low the oil level is and how much oil is left in the oil tank, the oil pump can ensure cooling, except those installed outside the oil tank for a long time.

The safety valve (pressure limiting valve) is installed at the outlet of the oil pump. The main function of this valve is to prevent the pressure in the oil pump from being too high, because some car owners don't know much about the replacement time of the gasoline filter and often forget to replace it, or because the quality of the added oil is not good, the pressure of the oil flowing out of the oil pipe becomes smaller, but the internal pressure becomes higher, which will lead to the damage of the oil pump or the rupture of the oil pipe.

The function of one-way valve (oil outlet valve) is to make it easier to start the engine next time, because this valve can only let the fuel flow out and the engine oil cannot flow back, so the inexhaustible fuel can be left in the oil pipe when the engine works, which is equivalent to discharging the fuel in the oil pipe in advance when the engine is started next time. Some models will be set to turn on the ignition switch for 3 seconds to let the oil pump run. At this time, we can hear the sound of the oil pump running.

Why is the gasoline pump broken?

The common causes of fuel pump failures are: fuel pump quality problems, fuel pump circuit problems, lack of filtering devices, poor oil quality, and long-term low fuel tank. Among them, the quality of the oil pump can be used for about 30-40 thousand kilometers. Before the warranty is issued, it is best to go to the 4S shop to check the oil pump, otherwise the maintenance price will be more expensive. Take Volkswagen Magotan as an example. If you replace the oil pump and the oil pump controller, it will cost more than 6,000 yuan!

No filter means that the screen of the oil pump is blocked. After the car has been used for a period of time, if the owner feels that the power and oil pressure of the car are insufficient through the oil pressure gauge, he can remove the oil pump to clean the filter screen, and do not replace the oil pump. The quality of oil products is poor, requiring car owners not to refuel from local small private gas stations, nor to add unqualified fuel according to the vehicle instruction manual.

Failure phenomenon of gasoline pump damage

1, fuel level display is not allowed.

At present, the gasoline pump basically integrates the oil pump motor, the gasoline filter and the oil level sensor. The working principle of the oil level sensor is to change the height of the oil float in the oil tank by changing the resistance value of the resistor, and then convert it into current and transmit it to the dashboard for display.

The main reason for inaccurate oil level is abnormal internal resistance, such as oil film polluting contact resistance, causing resistance to become larger or directly falling off to open circuit, or loose contact of fixed spring.

2, the engine can't start and the acceleration is poor.

If the oil pump can't start, it is mostly caused by insufficient pressure. The main reason is that the upper and lower shells fall off. When the heating temperature is different, the solder joint on the shell is not firm, which leads to cracking, fuel leakage and oil supply difficulty. If the gasoline filter is blocked, the motor speed drops and the oil supply pressure drops, using highly corrosive fuel (such as gasoline with more methanol) will make the chemical adhesive attached to the filter block the filter.

3. The oil pump makes a sound and does not work.

The abnormal noise and non-operation of the oil pump are mainly due to the abnormal wear of the motor carbon brush commutator, which will lead to the rotor being stuck, the rotating speed being obviously reduced, and the armature rotor running abnormally. And the most serious thing is to cause the engine to stall. If this is the reason, we can knock on the oil pump, temporarily let the oil pump run, and then slowly drive it to the repair shop for maintenance. The solution to this problem is to avoid using inferior fuel and replace the carbon brush commutator with good quality and reliable technology.

Summary: The fault phenomena of automobile oil pump are: inaccurate oil level display, poor engine starting acceleration, abnormal sound of oil pump, non-working, etc. If the gasoline pump fails, the gasoline can't be supplied normally and the engine works badly, which will bring great changes to the owner. If the above faults occur, I hope the owner can repair the car in time.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.