An example to explain the trouble shooting method of diesel engine fuel injection pump of constructi

The fuel injection pump is an important part of the fuel system of the diesel engine. Its working condition directly affects the power, economy and reliability of the diesel engine. During the maintenance, some repairmen didn't pay much attention to the fuel injection pump, which caused some faults artificially.

Here are only three examples for reference when finding faults.

(1) A 6135k-9a diesel engine equipped with zl50cii loader has no obvious fault during idling operation, but it makes a "sudden" noise as soon as it accelerates, and the smoke exhaust color is white or black, which is extremely unstable. At the beginning, it is considered that the injection timing is wrong, but after readjusting the injection timing, the fault is still the same; after checking the low and high pressure oil circuits, no problem is found. Finally, when removing the fuel injection pump, it is found that the lock nut at the end of the fuel injection advance is loose, the key slot between the fuel injection advance and the camshaft of the fuel injection pump has been widened due to wear, and the thickness of the semicircle key is less than half of the original. After re milling and key matching, the fault disappears. It is understood that the fuel injection pump of this engine has just been repaired. The direct cause of this fault is that the maintenance personnel did not tighten the lock nut according to the specified torque when installing the extended fuel injection advance device, so that the wear of the keyway and the woodruff key was intensified due to the loose coordination between the fuel injection advance device and the camshaft during the speed regulating operation of the engine, resulting in the unstable fuel injection timing.

(2) A 6135k-12c diesel engine is installed on a TL180 bulldozer. Its fuel injection pump model is bh6b100ys490. During an engine overhaul, the fuel injection pump and fuel injector were calibrated on the test bench. After the engine is run in, the bulldozer is put into earthwork operation, but it is unable to work because of the engine's working weakness, and the acceleration is poor when the engine blows the accelerator with no load. After inspection, the engine and fuel injection timing are normal, there is no leakage in the oil circuit, no problem in the governor, fuel injection pump, low pressure and high pressure oil circuit, etc., so it is suspected that the fuel volume under rated working condition may be adjusted too low during pump calibration. Therefore, the fuel injection pump was disassembled every year and recalibrated on the test bench. It was found that it was the pump calibrator who mistakenly lowered the rated working condition of the fuel injection pump by 6ml / 200 times. After readjusting, install the fuel injection pump back. When testing the machine, the operation is normal and powerful.

(3) A W4-60C excavator equipped with F6L912 diesel engine suddenly stalled on the way to the construction site, and then started several times but failed to start. Observe the exhaust condition, but there is no smoke. It is preliminarily determined that the oil circuit is faulty. During the inspection, pump the oil by hand, the result is that the oil output is good, and there is no air leakage or blockage in the oil circuit; when the speed control handle is swung, the oil volume regulating rod of the injection pump does not respond. When the governor was disassembled, it was found that the connection between the oil supply pull rod and the speed regulating lever was loose and the pin was broken. Reconnect the oil supply rod and speed control lever, and lock them with new pins. They start quickly when starting, indicating that the fault is eliminated. The reason for this failure is that the maintenance personnel did not replace the new pin as required when assembling the governor, but still used the original removed and cracked pin as a new one, resulting in pin fracture, loose connection between the oil supply pull rod and the speed control lever, resulting in the failure to start.