The function of the gasoline pump is to suck the gasoline out of the tank and send it through the pipeline and the gasoline filter to the floater chamber of the carburetor. It is because of the gasoline pump that the gasoline tank can be placed in the rear of the car far away from the engine, and lower than the engine. According to the different driving modes, the gasoline pump can be divided into two types: mechanical drive diaphragm and electric drive type.
1. The cause of the damage of the gasoline pump
The fuel delivery of EFI engine is pressure adsorption by electric gasoline pump installed in gasoline tank. Its motor part is also soaked in gasoline and cooled by gasoline to the high temperature generated in its operation. In view of this working principle, it is easy to damage the following principles.
1, long term fuel lamp alarm is not timely refueling, causing motor part of no gasoline cooling, burn out motor and suction diaphragm;
2, unclean gasoline plugging the suction pipe and diaphragm;
3, one of the key points, some owners of long-term open fire switch, engine ignition, sitting in the car listening to the stereo and conversation, because the circuit is switched on the gasoline pump began to work to release the pressure and pressure drop diaphragm motor burned or burned, as far as I know, as long as there is a domestic brand of gasoline pump manufacturers the quality is reliable, if you pump repeatedly damaged, please take a look at your habits.
The cause of the damage of the gasoline pump and the method of overhaul
Two. The maintenance of the gasoline pump
1. Repair of the housing of gasoline pump
(1) check the fuel pump with the upper shell and the lower shell flatness error of plane, is usually a combination of plane on the plate, with the feeler gauge measurement, the flatness error should be less than 10mm. If the excessive difference, it will cause gas leakage, oil seepage, affect the oil output of the gasoline pump and oil pressure. Therefore, if exceed the prescribed requirements, can be placed on a flat plate fine abrasive grinding.
(2) the plane of the shell and the cylinder body, its plane degree error should not be more than O.20mm. The method of inspection and repair is the same as above.
(3) the axial clearance in the rocker shaft rocker check, with measuring feeler inserted between the rocker arm and the shell, the clearance should be no more than 0.80mm. If the requirements are exceeded, the gasket of the same thickness may be placed on both sides of the rocker arm.
(4) the shell crack or notch should be replaced or bonded with epoxy resin adhesive. If the screw hole on the shell is damaged, the shell should be replaced or the screw hole should be repaired.
2. The overhaul of the rocker arm
The plane in which the rocker arm of the gasoline pump is in contact with the eccentric wheel will shorten the working stroke of the diaphragm and reduce the pump oil. The wear of the rocker arm should be surfacing if it is more than 0.2Omm. After welding, the Ra value of surface roughness should not be greater than 2.5μ m.
The radial clearance of the rocker arm and the rocker shaft should not be more than 0.1Omm. There should be no gap between the shaft of the rocker arm and the bearing hole of the shell. If the former exceeds the specified requirement or the latter has clearance, the hole can be enlarged and the rocker shaft of the larger size can be replaced.
3, the inspection and repair of the oil valve
The inlet and outlet valves are worn or corroded by acid substances in the gasoline, which are blocked by gum and other fouling. They are closed, affecting oil output and oil pressure. Oil valve damage should be replaced.
4, examination of diaphragm and diaphragm spring
The diaphragm is broken, hardened and metamorphosed, and should be replaced. After the diaphragm spring is used for a long time, the elastic strength is weakened. Therefore, the free length and performance of the engine should be checked when the engine is overhauled. It is required that the diaphragm spring should have enough tension, insufficient tension or corrosion, and the new product should be replaced.
5, performance test of gasoline pump
After the gasoline pump is fitted, the performance test should be carried out, preferably on a special test bed. In the test, the installation size of the gasoline pump should be in accordance with the actual installation requirements of the gasoline pump on the engine. When an eccentric wheel is driven to drive a gasoline pump according to the specified speed, its technical requirements should be in accordance with the technical requirements. When the required pressure is reached, the pump oil lmin is stopped, and the pressure drop must not be greater than 2.66kPa within this time. There must be no oil infiltration in 3min.
In the absence of special test case, also can use the experience of test: when the mouth sucked into the oil port can suck the tongue; blowing out of the oil port when the wind does not move, said the burst out of the oil valve with good sealing performance. The oil intake is immersed in water or gasoline, the arm is pressed with the hand, and the oil is quick and powerful without the bubble. It indicates that the gasoline pump has good performance. Otherwise, replace the gasoline pump.
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