The diesel engine black smoke have few reasons.according to usually problems accured,have follow reasons:

1.the fuel injection system problem

2.Burning system problem

3.Intake system problem

4.Exhaust system problem

5.Others for example diesel quality problem,the parts matching problem

How to confirm exactly reason and settle it?

1) Incorrect fuel supply advance angle. The fuel supply advance angle of diesel engine is the best advance angle to ensure full combustion of fuel after entering the cylinder. The advance angle is also different for different models. Incorrect injection advance angle will lead to insufficient and incomplete fuel combustion of diesel engine, which will lead to black smoke of diesel engine. a. The fuel supply advance angle is too large. If the fuel supply advance angle of the diesel engine is too large, the compression pressure and temperature in the cylinder are relatively low, which will directly affect the combustion performance of the fuel. The early combustion of the diesel engine increases, the fuel combustion is incomplete, and the diesel engine emits serious black smoke. In addition to the black smoke fault of the diesel engine caused by the large fuel supply advance angle, there are also the following phenomena:. There is strong combustion noise, the diesel engine power is insufficient, and the fuel consumption increases significantly . the interface of exhaust pipe is wet or dripping oil The exhaust temperature may be high, and the exhaust pipe may burn red. B. the oil supply advance angle is too small If the fuel supply advance angle of the diesel engine is too small and the best time is missed when the fuel is injected into the cylinder, the post combustion of the diesel engine will increase, and a large amount of fuel will be discharged from the cylinder before it is fully burned, and the diesel engine will seriously emit black smoke. In addition to the black smoke fault of diesel engine caused by the small fuel supply advance angle, there are also the following phenomena:. The exhaust temperature is high and the exhaust pipe is red
. the overall temperature of the diesel engine is high, the diesel engine is overheated due to the increase of aftercombustion, the power of the diesel engine is insufficient, and the fuel consumption increases significantly
Troubleshooting: if it is confirmed that the black smoke of diesel engine is caused by incorrect fuel supply advance angle, the fault can be eliminated as long as the fuel supply advance angle is adjusted to the design angle.

(2) The plunger or delivery valve of the fuel injection pump is seriously worn
Serious wear of individual or all fuel injection pump plungers or outlet valves will lead to the decrease of pump oil pressure of fuel injection pump, so that the built-up pressure of fuel injector (nozzle) lags behind, the fuel combustion is insufficient, and the aftercombustion increases, so the diesel engine emits serious black smoke. The plunger and outlet valve of individual cylinders have problems, which will not have a great impact on the use of the diesel engine except for the black smoke of the diesel engine. However, if the plunger and outlet valve of the fuel injection pump are seriously worn, there are the following phenomena while causing serious black smoke of the diesel engine:. It is difficult to start the diesel engine
. the amount of lubricating oil of diesel engine may increase. The power of diesel engine is insufficient
. the exhaust temperature of the diesel engine is high, and the exhaust pipe may burn red. The diesel engine may overheat due to the increase of aftercombustion The basic method to confirm that the black smoke of diesel engine is caused by the wear of plunger or oil outlet valve is as follows:
A. remove the exhaust pipe of the diesel engine, start the diesel engine at low speed, carefully observe the smoke exhaust condition of each exhaust port of the diesel engine, find out the cylinder with large smoke exhaust, and replace the fuel injector of the cylinder (which can be interchanged with the cylinder without black smoke). If the cylinder still emits black smoke and the other cylinder does not emit black smoke, It can be confirmed that there is a problem with the plunger or outlet valve of the fuel injection pump of this cylinder.   
B. without removing the exhaust pipe, use the single cylinder fire extinguishing method to preliminarily confirm whether there is a problem with the plunger / oil outlet valve or the fuel injector (nozzle). The specific method is to start the diesel engine at low speed, cut off the oil cylinder by cylinder, and observe the change of the smoke at the outlet of the exhaust pipe. For example, if the smoke of the diesel engine decreases after the oil is cut off in a cylinder, This indicates that there is a problem with the fuel supply system (plunger / outlet valve or injector) of the cylinder. Troubleshooting: when these problems occur during the operation of the diesel engine, the fuel injection pump should be checked. If it is confirmed that the fault is caused by serious wear of plunger and outlet valve, the fault can be eliminated after overhauling the fuel injection pump.   
Special note: when overhauling the fuel injection pump, replace the plunger, oil outlet valve and relevant gaskets in a complete set (all), check the oil supply angle of each cylinder and adjust the oil supply as required.

(3) Fuel injector (nozzle) problem
A. poor atomization, jamming or serious oil dripping of fuel injection nozzle
When the fuel injector (nozzle) of an individual cylinder is damaged, that is, when the fuel injector (nozzle) of a cylinder is poorly atomized, stuck or dripping seriously, it will cause incomplete fuel combustion of the cylinder and cause serious black smoke of the cylinder. When there is a problem with the fuel injector (nozzle), in addition to causing black smoke from the diesel engine, there are the following phenomena:
. the interface of exhaust pipe is wet, and diesel oil may drop in serious cases. The piston of dropping cylinder may burn top or pull cylinder. The cylinder may have strong combustion noise {B and incorrect injection pressure
Incorrect injection pressure (too large or too small) will affect the pressure build-up time of the injector, delay or advance the fuel supply advance angle, and make the diesel engine emit black smoke during operation. High injection pressure may delay the start time of injection and increase the aftercombustion of diesel engine. Injection pressure
Why is the fuel burner always off
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The force is too small, which may advance the start time of fuel injection and increase the early combustion of diesel engine. The problems and phenomena caused by the two are similar to the incorrect oil supply advance angle mentioned above.   
The method to confirm whether there is a problem with the injector (nozzle) of a cylinder is basically the same as the method to confirm whether there is a problem with the plunger / outlet valve, except that after the injector is exchanged, the cylinder no longer emits black smoke and the other cylinder emits black smoke, indicating that there is a problem with the injector (nozzle). Troubleshooting: replace the fuel injector or fuel injector assembly of the cylinder. When replacing the fuel injector, ensure that it is a qualified product of the same kind, strictly check and adjust the fuel injection pressure as required, carefully observe the atomization quality of the fuel injector or whether there are problems such as low-speed oil dripping, so as to ensure that the fuel injector (nozzle) with high quality is used.