The engine can not start Engine construction on the construction machinery are basically similar, there are commonly used high-pressure oil pump as the representative of traditional diesel engines and represented by PT pump Cummins Engine. In the battery power is sufficient, there is fuel in the fuel tank and the fuel tank switch is open, and repair the correct size of the various components, the engine can not start the reason can be connected to start the exhaust pipe to determine whether there is smoke. (1) Exhaust pipe emits black smoke If the black smoke is discharged, the fuel system is working properly and the ignition timing is accurate. In this case, you can use manual pump to continuously pump oil (referring to the traditional diesel engine) and exclude the air in the high pressure pump , You can start. If smoke is emitted but can not be started, first check whether the engine and the transmission are separated; that is, whether the clutch is open or not. Such as an Ingersoll Rand P600 air compressor black smoke but can not start, check the oil on the circuit are normal, the engine and air compressor clutch device is not separated, starting load is too large, can not start; will After the clutch device is disengaged, the engine starts very smoothly. Second, the ignition timing should be checked for high-pressure oil pump after the correction, the assembly sometimes wrong because the signs are often wrong, resulting in improper ignition timing, leading to failure to start. Such as a CA30 roller pump can not be installed after the school started (the engine is Deutz F6L912), because the timing gear chamber of the meshing gear on a wrong tooth; the correct assembly, the start back to normal. (2) Exhaust pipe without exhaust If the exhaust pipe without smoke, indicating that a system is not working properly. At this time, you can open the manual pump oil pump to observe whether there is high-pressure oil pump fuel outflow, whether the flow smoothly, while opening the high-pressure oil pump outlet, observe the cylinder fuel supply, if the fuel flow is normal, and high-pressure pump out Very little oil out of the oil, you can determine the high-pressure pump piston wear out of limit, you can replace; If manual pump oil from the high-pressure oil pump outlet at the oil, then the valve is not tight, Serious discharge, must be replaced or grinding, diesel engine may start normally. If you check the fuel system is working properly, you should consider other systems. Such as a D85-18 bulldozer, the power of the aircraft is Cummins NT855 engine, then the fault phenomenon is: normal work engine stalling, want to start when you can not start and do not smoke. Oil pipeline inspection and pump test results are normal, and a lot of fuel flow, indicating that the fuel system is no problem. Open the valve cover and found just adjusted valve clearance has become very large, a phenomenon that the valve body problems. Remove the valve rocker arm, only to find the inlet and exhaust valve rams have been bent, indicating a problem with the timing gear room. Disassemble the timing gear chamber and found that the semi-circular key of the fixed crankshaft drive gear was polished down and the drive gear was moved outward by 10mm to make the entire timing system. Fuel system, intake system and exhaust system are disorder, and this is the root cause of the engine can not start. 2. Inability to work After the start of construction machinery weakness, mostly due to fuel system problems. The obvious characteristics of this type of failure are: the engine runs normally at no-load, and after work load, it shows work weakness, the engine should be turned off and so on. Examples of such troubleshooting are as follows: (1) A Russian-made AI70 bulldozer, drivers often feel the machine bulldozed when working, the engine has to turn off the feeling. Inspection method: First of all, open the manual pump oil, oil out of tubing, oil normal, so that the machine to continue working, but for a while will not work. According to this phenomenon, presumably mechanical pump out of the fault. Dismantling the mechanical pump, we found that the four spring break into sections, only a small part of the work. Re-install a return spring, the fault can be ruled out. (2) A TI20 bulldozer, the engine runs normally at no load, but only with 1 block when the load is loosening, if the work in D block is to turn off the flame. Inspection method: First open the manual pump oil, the system has no air, working properly; After replacing the fuel coarse, fine oil filter, the small load when the bulldozer work basically normal engine work, but still not normal under heavy load conditions. In this regard, some people think that the lack of high-pressure oil pump, the analysis that is oil fault. As a result, the oil filter pipe between the mechanical pump to remove the inspection, it was found that the rubber tube aging, proved to be due to poor fuel supply to form a throttle, resulting in insufficient oil, resulting in bulldozers work weakness. After replacing the tubing, the work returned to normal. (3) A Hitachi UHI71 excavator is operating normally at no load, but once burrowed, it smokes black smoke and becomes weak. Inspection methods: First of all, a comprehensive inspection of the oil supply system, the result is normal, indicating that the engine itself is no problem; the observation found that the exhaust pipe at the coke more, so that the exhaust resistance is too large, resulting in decreased power and black smoke . After opening the muffler, cleared coke, the work returned to normal. (4) A Steyr 1491 dump truck is operating normally at no-load and is shut-off at heavy loads. Inspection method: pump oil with a hand pump, found in the fuel in the air, the other parts of the normal work. Investigation, the tubing directly from the tank received mechanical pump (that is, the fuel does not pass the fuel filter), and then start the car test, the results of the car is working properly, indicating that there is a leak in the fuel pipeline; and then with the corresponding diameter Transparent plastic pipe connected to the tank to the coarse filter (pipe fittings used to replace the old connector can be), did not find bubbles, and transparent plastic pipe connected to the coarse filter to the fine oil filter, with a manual pump When the oil was found to have continuous bubbles appear, after inspection, joints at no problem, but the fine filter itself has leaks. After replacing the fine filter, the work returned to normal.