④ high ambient temperature, small fuel tank, poor cooling, will make the pump heat. Should be handled separately. 5, the main parts of the repair (1) gear ①tooth repair: remove or remove with a fine sand cloth or whetstone polygonal area, and then the gear meshing surface replacement orientation and appropriate research, the final clean ; Severe wear parts that can be observed with the naked eye should be replaced. ② end face repair: gear end face due to bearing or front and rear relative rotation of the cover and wear, light from the line, available grinding method to start burr marks grinding and polishing; serious wear, the gear should be placed on a surface grinder Sharpen. It should be noted that the two gears must be grinded on the surface grinder at the same time in order to ensure that the thickness difference between the two gears is within 5μm. At the same time, the perpendicularity of the end surface to the hole and the parallelism of both end surfaces must be 5μm Within the range, and sharp edges with stone will be blunt, but must not be chamfered, so burr-free, flash can be. ③ When the gear meshing surface wear, the use of whetstone will wear away the burr; the same time, the exchange of gear meshing position, so that the original non-meshing work toothed surface meshing work, so that not only to ensure its original working performance , But also extend the working life of gear. (2) pump body wear and tear, mainly in the cavity and gear round contact that side, and occurred in the suction side. If the pump body is of symmetrical type, the pump body can be overturned by 180 degrees and then reused. If the pump body is asymmetrical, wear the bronze alloy plating or brush plating method to repair the wear parts of the bore in the pump body. (3) Bearing race Bearing race wear and tear generally in contact with the gear that end face and contact with the needle on the hole. Face wear or pull the hairline, the four bearing rings can be placed on a surface grinder, the gear does not come into contact with the side of the bristle face polished, the accuracy should be guaranteed in the 10μm range. Generally smaller bearing race wear, if serious wear and tear, grinding; or appropriate to increase the aperture and re-election needle; or replace the bearing race. (4) long, short axis length, short axis failure, mainly in contact with the needle roller bearings wear. If minor wear, use polish repair (and replace the new needle roller bearings); if it is worn out or broken, use chrome plating to repair or rework. Re-processing, to meet the long and short axis of the keyway on the axis of the parallelism and symmetry requirements; installed in the shaft key and the gear keyway with the gap can not be too large; shaft not in the gear bore Produce radial swing; journal and mounting gear part of the mating surface with the coaxiality of not more than 10μm, coaxiality at both ends of the journal shall not exceed 20-30μm.