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I. Reasons for loud noise in self-priming pumps: If the head of the self-priming pump is insufficient, the pump is unable to draw water from the well, which results in loud noise from the pump. Solution: By replacing it with a high-power water pump of appropriate size, the problem of loud noise from the water pump can be resolved. Reason: There is air ingress or leakage at the connection in the pipeline from the well water level to the pressure tank, allowing air to enter and causing noise in the water pump. Solution: Recheck the pipeline and connections from the water well level to the pressure tank for any air leaks, and then reconnect them properly. II. If the self-priming pump will not start, the power supply should be checked first: ensure that the connections are secure ； Are the switch contacts tight? ； Is the fuse blown? ； Check whether there is a phase imbalance in the three-phase power supply. In the event of an open circuit, poor contact, blown fuse, or missing phase, the cause should be identified and repaired promptly. Next, check for mechanical faults within the water pump itself; common causes include an overly tight packing or blockages caused by debris trapped between the impeller and the pump casing ； The pump shaft, bearings, and leak reduction rings are rusted ； Severe bending of the pump shaft, etc. Exclusion method: Relax the filler and clear the water diversion channel ； Disassemble the pump body to remove debris and rust ； Remove the pump shaft to correct it or replace it with a new one. III. Reasons for heat generation in self-priming pumps: damaged bearings ； The clearance between the rolling bearing or bracket cover is too small ； The pump shaft is bent or the two shafts are not aligned ； The tape is too tight ； Lack of oil or poor oil quality ； The balance holes on the impeller are blocked, causing the impeller to lose its balance and increasing the thrust in one direction. Exclusion method: Replace the bearing ； Remove the rear cover and install shims between the bracket and the bearing housing ； Inspect the pump shaft or adjust the concentricity of the two shafts ； Adjust the tape tension appropriately ； Fill with clean butter, with the butter occupying about 60% of the space within the bearing ； Remove the blockages from the balance hole. IV. Problems with the motor section: No response after powering on. Reason: In most cases, it is caused by short circuits in the power plug, power leads, and motor windings. Problem: Difficult to start or fails to start, accompanied by a \"buzzing\" sound. Exclusion method: During maintenance, a small bamboo piece can be used to quickly move the fan blades in the direction of rotation; if the motor starts spinning immediately, it indicates that the starting capacitor or the starting winding is damaged, and it is necessary to replace it with a capacitor of the same capacity or repair the starting winding ； If the motor gets stuck, it is usually due to mechanical faults in the motor and pump head, such as damaged bearings or a stuck impeller. Problem: The motor runs, but at a low speed; the casing overheats and there is a burnt smell. Exclusion methods: In most cases, it is caused by a short circuit in the motor windings; the motor should be disassembled, and depending on the extent of the damage, repairs such as welding, using jumpers, isolation, or rewinding should be carried out. Problem: High noise and vibration during operation. Exclusion methods: In most cases, it is due to damaged bearings or an improper fit between the bearings and the housing; the motor needs to be disassembled for inspection, and if the bearings are damaged, they need to be replaced ； If the bearing runs on the outer circumference, the mating surface of the pump casing can be treated with chiseling ； If the bearing runs on the inner circle, the worn area of the motor shaft can be treated with knurling; in cases of severe wear, it can be repaired by first performing surfacing and then turning. V. Reasons for insufficient flow in self-priming pumps: Incompatible drive speed or belt slippage, resulting in a low rotation speed ； The installation angle of the axial flow pump blades is too small ； Insufficient head, too long piping, or straight bends in the piping ； The suction lift is too high ； Local blockage of the bottom valve, pipelines, and impeller, or damage to the impeller ； The water outlet pipe is leaking severely. Exclusion methods: Restore the rated speed, remove oil buildup from the belt, and adjust the belt tension properly ； Adjust the blade angle, lower the installation height of the water pump, shorten the pipelines or change their curvature ； Seal the leak in the water pump by compressing the packing ； Remove the blockage and replace the impeller ； Replace the leak-reducing ring to seal the leak. VI. Reasons why a self-priming pump cannot draw water: air is present inside the pump or in the inlet pipe, the bottom valve does not close properly resulting in insufficient water filling, there is severe leakage in the packing of the vacuum pump, or the gate valve or check valve does not close properly. Exclusion method: First increase the water pressure, then fill the pump body with water, and finally turn it on. At the same time, check whether the check valve is airtight and whether there are any air leaks in the pipes and connections; if leaks are found, disassemble them, apply lubricant or sealant to the connections, and tighten the screws. Inspect the oil seal ring of the water pump shaft; if it is severely worn, replace it with a new one. The pipeline is leaking fluid or air. The nut might not have been tightened properly during installation. If the leakage is not severe, cement can be applied to the area where air or water is leaking, or a cement paste mixed with asphalt oil can be used. For temporary repairs, some wet mud or soft soap can be applied. If there is leakage at the joint, the nut can be tightened using a wrench; if the leakage is severe, the assembly must be disassembled again and the cracked pipe replaced ； Reduce the head by submerging the pump outlet 0.5m underwater. VII. Problems with the pump head: The motor operates normally, but the water output is low or there is no water output at all. In such a situation, the seal of the water pump should be checked first. To do this, unplug the power cord first, cover the water intake with your hand, fill the pump with water, then hold the outlet with your mouth and blow hard into it to see if there is any leakage from the pump head; the area where leakage occurs is where the seal is damaged. Common faulty parts include the water inlet gasket, the water outlet gasket, and the impeller cover gasket, which should be replaced during maintenance. If there is no water filling phenomenon, it is usually due to damaged impellers, erosion of the water-sealing partition between the suction chamber and the discharge chamber, wear down of the water-sealing partition at the pump head, or an increased gap between the impeller and the pump casing; in such cases, the impeller and pump casing should be replaced. When replacing the foot wheel, care should be taken to thoroughly remove any remaining copper blades inside the pump, to prevent further damage to the new impeller. Question: The casing is charged. In most cases, it is caused by a damaged water seal, with water seeping into the motor through the motor shaft and thereby deteriorating the motor’s insulation properties. This can be repaired by replacing the water seal or drying the motor. It should be noted that, due to prolonged exposure to water and operation in outdoor conditions, water pumps are highly susceptible to moisture absorption, which can lead to a deterioration in their insulation properties. To ensure personal safety, electric self-priming pumps must be properly grounded. Question: Reason for severe vibration in self-priming pumps: Unbalanced electric rotor ； Poor coupling fit ； Bearing wear and bending ； The parts of the rotating mechanism are loose or damaged ； Reasons such as loose pipeline supports. Exclusion methods: Adjustments, repairs, reinforcement, straightening, replacement, and other methods can be employed respectively. VIII. Solutions for no water flow or low water volume: First, check how much the current drawn by the pump differs from its normal operating current. If it is lower than during normal operation (essentially 2.3 times the normal current), then there may be issues such as worn impellers or a clogged check valve at the top of the pump head. If the current is as high as during normal operation, then there could be problems such as leakage at the pipe gasket, leakage in the pipes, or leakage in the pump body. If the current is higher than normal during operation, it can basically be determined that it is a problem caused by wear and tear of the vulnerable components. As an additional point, if the cable is damaged, the water flow will remain the same as usual, but the current will increase. IX. Four main reasons for overheating of the auxiliary drive motor: The first is a problem related to the power supply – either the voltage is too high or too low. Under certain loads, if the voltage deviates beyond the range of +10% to -5% of the rated value, it can cause the motor to overheat ； If the three-phase voltage of the power supply is asymmetric, with an imbalance between the phase voltages exceeding 5%, it can cause the windings to overheat ； Operation with a missing phase: Experience shows that over 85% of agricultural motors get damaged as a result of operating with a missing phase. Exclusion method: A phase loss protection device should be installed on the motor. The second reason is related to the water pump: an inappropriate power level is used, meaning a motor that is not strong enough for the task is employed; as a result, the motor operates under overload conditions for extended periods, causing its temperature to rise excessively ； Motors that are started too frequently, or those designed for short-duration or intermittent operation, are forced to work continuously. Exclusion methods: The number of starts should be limited, appropriate thermal protection should be selected, and the motor should be used according to the rated specifications indicated on it. Third is a problem with the motor itself: an incorrect wiring method, where a delta connection was mistakenly used in place of a star connection, causing the motor’s temperature to rise rapidly ； The stator windings may suffer from inter-phase short circuits, turn-to-turn short circuits, or local grounding; in mild cases this causes localized overheating of the motor, while in severe cases it leads to insulation damage ； If the squirrel-cage rotor has broken bars or defects, the core temperature rises rapidly after the motor has been running for 1 to 2 hours. Exclusion method: If there is a malfunction in the ventilation system, check whether the fan is damaged, whether its rotation direction is correct, and whether the ventilation ducts are blocked ； Bearing wear and rotor eccentricity cause the stator and rotor cores to rub against each other, generating metallic knocking sounds; the temperature of the cores rises rapidly, and in severe cases the motor starts to smoke or even the windings get burned out. Fourth is the issue of the working environment: moisture in the motor windings, or dust and oil residues adhering to the windings, lead to reduced insulation. The insulation resistance of the motor should be measured, and it should be cleaned and dried ； The ambient temperature is too high. When the ambient temperature exceeds 35°C, the high inlet air temperature can cause the motor to overheat. Exclusion method: Efforts should be made to improve their working environment. Such as setting up shelters for shade, etc. Friendly reminder: The above outlines the nine most common faults that occur in self-priming pumps along with their corresponding solutions. If a fault arises due to electrical issues, it should be repaired by an electrician with professional qualifications; those with only limited knowledge should not attempt repairs on their own to avoid potential accidents that could cause injury.