Fault performance:
When the excavator is working, the maximum speed of the engine can only reach 1600r / min, and the power drops seriously
Analysis of difficult acceleration of excavator engine:
1 at the beginning, it is suspected that the cylinder pressure of the diesel engine may be insufficient The pressure of each cylinder was measured with the cylinder pressure gauge, and the results showed that the cylinder pressure decreased, but it was still within the specified range of use. According to the practical experience, the above-mentioned defects were not caused
2. It is also suspected that the diesel filter of the low-pressure oil circuit may be blocked, resulting in the lack of high-speed fuel supply for the diesel engine. The diesel filter was removed and replaced with a new one, but the result was no effect.
It seems that most of the problems are caused by the fuel injection pump The fuel injection pump of the diesel engine is of rotor distribution type. After the pump is removed from the diesel engine and cleaned, it is installed on the fuel injection pump test bench for calibration It is found that when the speed control handle is at the large throttle position and the pump speed is above 800r / min, the fuel injection pump gradually stops supplying oil, which indicates that there is indeed a problem with the fuel injection pump
4. The fuel injection pump was disassembled and inspected. It was found that the sliding vane fuel delivery pump was significantly worn, and no abnormality was found in other parts After replacing the new sliding vane oil transfer pump, it was found that the oil supply was normal when the pump speed was 300r / min when it was verified again on the oil injection pump test bench However, when the speed control handle is pushed to the large throttle position and the pump speed is gradually increased to more than 400R / min, the fuel supply of the fuel injection pump is gradually stopped. It is the same through several experiments
5. After analysis, it is believed that there may be a problem with the solenoid valve on the fuel injection pump. However, the solenoid valve core and the return spring were removed and the test was conducted from the beginning. The problem remained
6 considering that the fuel injection pump will stop supplying oil gradually when the pump speed reaches above 800r / min when the pump is tested on the fuel injection pump test bench before the parts are replaced After replacing the new oil pump, when the pump speed reaches more than 400R / min, the oil pump will gradually stop supplying oil. Therefore, it is doubted that the new oil pump may have problems in quality and installation orientation
7. The fuel injection pump was disassembled and inspected from the beginning. It was found that the new oil transfer pump cover was not installed incorrectly, and the installation orientation of the slide in the rotor groove was correct. When the bias ring was inspected, it was found that the installation orientation was wrong The installation reference hole of the bias ring is installed on the left side facing the pump drive shaft. It seems that this is the root cause of the problem
8 to do this, install from the beginning When the bias ring on the oil transfer pump is installed in the pump housing, the installation reference hole on the bias ring is installed on the right side of the pump housing (facing the direction of the fuel injection pump drive shaft). This is because the rotation direction of the pump drive shaft is right turn (marked as R). After the pump is installed, it is corrected on the fuel injection pump test bench. After testing, the oil pressure in the pump appears normal. When the pump speed increases to 1300r / min, the oil supply is still normal. Install the pump on the diesel engine and try again, The idling speed can reach 4600r / min, and the fault is eliminated
