Common faults and maintenance technology of automobile engine
Engine failure is one of the common failures of vehicles, especially vehicles that have been driving for more than 3 years or more than 50,000 km. Military transport vehicle is one of the main vehicles in the army at present. In the process of vehicle development, in order to meet the actual use requirements of the army in combat, training and many guarantees, the left and right split double fuel tanks were adopted. In the actual use process, due to the influence of many factors, the engine failure rate of this car further increases, so this paper launches the following analysis.
After a preliminary inspection, it was found that the circuit, lighting and related instruments of the car were normal. The battery voltage and line connection are in good condition, but the engine does not start normally when the ignition switch is placed in the starting gear. After the auxiliary start button is pressed, the starting gear is toothed. By resetting the starting gear, the vehicle was successfully started by pressing the auxiliary starting button again. Through the analysis of the above fault phenomena, it is judged that the fault type of the engine is the loose ground wire of relay or open coil.
In addition, check that the oil quantity in the fuel tank is normal, the oil path between the fuel tank and the high-pressure oil pump is in normal condition, and the supply pipeline is free from damage, deformation, loose joint and oil leakage. After the oil inlet pipe joint of the fuel injection pump was removed, the oil was pumped by the hand pump, and bubbles were found. Remove the oil inlet pipe joint of the primary fuel filter, and pump air towards the fuel tank, which is completely smooth and free of air leakage. Remove the oil outlet pipe joint of the primary fuel filter, put it in the oil basin, pump oil with the help of the hand pump, and find that the oil outlet is normal and the bubbles disappear. Combined with the above fault phenomena, it is further determined that the failure of the engine to start normally is also directly related to the failure of the primary fuel filter. Therefore, when determining the cause of starting failure of automobile engines, this paper analyzes the above two problems as follows.
Analyze the cause of failure from the primary fuel filter
According to the above inspection, it is concluded that the fault lies in the primary fuel filter. Check that the connecting bolts between the primary fuel filter base and settling cup are not loose and that the primary fuel filter base, oil pipe joint, settling cup and rubber sealing gasket are intact. In addition, the failure of the primary fuel filter can easily lead to the problem of a low-pressure oil circuit, so it is necessary to combine the failure of a low-pressure oil circuit when analyzing the cause of the failure. The low-pressure oil circuit includes an oil tank, fuel strainer, oil transfer pump, fuel filter, oil-water separator and fuel injection pump. Considering that the engine starts up to meet the conditions, the fault may be caused by air leakage in the pipeline from the oil tank to the oil transfer pump, or the performance of the rubber gasket between the base of the primary fuel filter and the precipitation cup deteriorates, which leads to the air entering the low-pressure oil circuit, which makes the engine unable to start normally.
Troubleshooting combined with engine starting system
According to the above fault types, the engine starting system can be divided into two parts: the starting circuit and the starter, and then the fault detection and elimination can be targeted. When the starting switch is turned to ST gear, the starting circuit and the nodes of the starter are measured by means of a multimeter. If the measurement result shows electricity, it means that there is no fault in the starting circuit; If the test result shows that there is no electricity, the cause of the fault should be further analyzed. When the start switch is turned to ST gear and the line is in a non-power state, press the auxiliary start button to check whether the line has power. If the test result is electrified, it means that the fault lies in the circuit between the start switch and the start relay. At this time, it is necessary to remove the black and yellow lines on the starting relay and test the lines. If the test result shows that there is electricity, it means that the fault lies in the starting relay. In this case, the troubleshooting scheme is to connect the ground wire and replace the starting relay. If the black and yellow line detection result of the starting relay shows no electricity, it is necessary to detect the wiring condition of the first group of harnesses in the harness junction box.
Troubleshooting of terminal equipment
The fault analysis and solution of the starting relay are as follows: press the auxiliary starting button, and the starting line is in a dead state, and the starting relay coil is normally energized. This phenomenon indicates that the starting relay terminal is in a dead state, the relay contact is ablated or the starting line is broken. In this regard, the troubleshooting methods are as follows: First, conduct a comprehensive inspection of the power supply of the starting relay; Secondly, make clear the actual ablation of starting relay contacts; Third, check the electrification of the wire between the starting relay and the automobile starter. According to the fault performance, it is necessary to connect the ground wire of the starting relay, and then replace the ground wire. The troubleshooting scheme of the starter is as follows: first, when the fault is not in the electromagnetic switch, measure the resistance of the pull-in and hold coils, and if there is an open circuit, the coils need to be replaced; Secondly, when the fault lies in the electromagnetic switch, it is necessary to disassemble the electromagnetic switch, clarify the ablation condition of the contact, and carry out corresponding grinding or replacement operation according to the actual situation.
To sum up, vehicle managers should consult relevant books as much as possible to analyze and eliminate various engine faults of automobiles, so as to accumulate rich experience and experience in engine fault detection and maintenance. In addition, the author suggests to do a good job in the daily maintenance of vehicles, and to solve the problems related to vehicle engine failure, use fault tree analysis method flexibly to complete the troubleshooting, so as to ensure that the vehicle equipment can be in a ready-to-use state.