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Fault analysis and inspection Some faults often occur during the use of gasoline engines, mainly due to the failure of the gasoline engine to start; insufficient engine power; unstable speed, fluctuating high and low, abnormal noise, etc. After discovering that the gasoline engine is malfunctioning, analyze it calmly, find the cause, and do not blindly disassemble it. The method of judging faults should be from simple to complex, from table to inside, so that the cause of the fault can be found accurately and timely, otherwise, some simple faults will be treated as complex faults, which will waste time and cannot be found. If it fails, sometimes the parts will be broken. Several common faults are analyzed as follows:

　　 1. Why can't the gasoline engine start? There are three main reasons why the gasoline engine can't start: the fault of the fuel system, the fault of the circuit system, and the insufficient compression force of the cylinder. In general, the three major faults will not exist at the same time. Therefore, when a machine fails to start, you should first determine the fault, determine which system the fault is in, and then take measures. Don’t be rushed, you can follow the steps below to check. ①First turn the starting wheel by hand. When turning the top dead center, it feels more laborious. After turning the top dead center, the starting wheel can automatically rotate through a larger angle, indicating that the compression is normal. For new machines or after overhaul In general, the compression force is good. ② There is no explosive sound in the cylinder when starting, the exhaust pipe is weak, and the exhaust gas is dry and tasteless. This phenomenon mostly indicates the problem of the oil system. Check whether the fuel tank switch is turned on, the amount of oil in the fuel tank, and whether the oil connection is loose. Press the carburetor enrichment lever several times to see if there is oil flowing out. When it is found that the above parts are normal and still unable to start, pour gasoline into the spark chamber hole and start again. If it still fails to start or it extinguishes after a few occasions when it smokes, it means that the metering hole in the carburetor may be blocked. Remove the float chamber and remove the metering hole and use it to blow or clean it. Never use a metal wire to pass it. Measuring hole. ③ When starting, there is no explosion sound in the cylinder or the explosion sound is cluttered with the carburetor or the silencer, and the gas emitted by the silencer is moist and smells of gasoline. Most of the above phenomena are faults of the circuit system. When there is no explosion, first remove the spark chamber, place the spark chamber on the spark plug guard on the high-voltage line, and contact the side electrode of the spark chamber with the metal part of the machine, and quickly turn the starting wheel to see if there is a blue spark jump However, if not, check the circuit components separately. For the old machine, if the electric circuit and oil circuit are normal and still cannot start, you can further judge whether the compression pressure is too low. At this time, you can remove the spark plug and pour a small amount of oil into the cylinder, and then install the spark plug. If it catches fire, it means that the cylinder is not well compressed. You should disassemble the cylinder head, check whether the cylinder head gasket is damaged, take down the cylinder, and check whether the piston ring and cylinder are over-weared. ④All parts are in good condition. Because the starting environment temperature is too low, the machine is too cold, the gasoline is not easy to atomize, and it is not easy to start. ⑤If the pipeline is not connected tightly, the oil is less and the gas is too much, or the air filter is clogged, the oil is too much and the gas is not easy to start. ⑥ The direction skills and starting speed of the starting rope also affect the starting ability. ⑦ It is not easy to start if the inner door opening is improperly blocked when starting.

　　2. The engine power is insufficient, and it is usually said that it is not powerful. There are five main reasons: ①The machine compression force is insufficient: the piston, piston ring, and cylinder are worn out. Replace with new ones. ②Wrong ignition time, too early or too late is not good for full power utilization. For new machines, the ignition time should be within the specified range (referring to the original platinum gasoline engine). Use the current inner rotor magneto (referring to the existing gasoline engine) The gap needs to be adjusted later. ③The mixture is too thin and too thick. ④ Insufficient crankcase pressure: oil leaks from the engine body, and the crankcase gasket is damaged. Replace it. The front and rear half of the crankcase leaked oil and the oil seal was damaged. Replace with a new one. ⑤The engine is overheated, and the machine should not be overloaded for a long time. Remove the carbon deposit on the cylinder head and the top of the piston in time.

　　 3. The gasoline engine is not running smoothly. ① The engine is knocking. , Pistons, piston rings and cylinders are worn too much, piston pins and pin holes are worn, or crankshaft spindles and needle bearings are worn. Repair or replace with new parts. ②There is a metal knocking sound (deflagration). The gasoline engine is overheated, the combustion chamber is carbonized, or the gasoline engine oil grade does not meet the requirements. Cool down, remove the carbon deposits of related parts or replace the specified brand of steam engine oil. ③The gasoline engine is out of fire. There is water or precipitated oil in the float chamber, the gap between the spark plug and the breaker is inappropriate, or the stator is loose. Remove the carbon deposits, adjust the gap or replace with new ones.