1, air filter clogging: air intake obstruction is the most common problem, because the air in the dust and particles in the air too much so that the filter element accumulates more dust and dirt, increasing the air intake resistance, resulting in insufficient supply of air, which also affects the combustion efficiency. Solution: Check, clean or replace the air filter element.

2, poor oil quality, carbon: If you add the poor quality of diesel fuel, then the mixture will produce carbon after combustion, and carbon will hinder the oil circuit, and lead to poor oil supply, may lead to the mixture is too thick and generate black smoke. Solution: Clean the fuel line or add fuel cleaner.

3, insufficient compression: valve, piston ring, cylinder liner wear, caused by insufficient compression pressure, compression pressure and temperature at the end of the compression does not meet the requirements of the fuel combustion conditions deteriorate, easy to produce black smoke. Solution: 4S testing is required to confirm the root cause of the problem and replace damaged parts.

4, poor injector work: poor injector work is mainly manifested in three aspects: one is the spray quality is poor; the second is the injection pressure is insufficient; the third is the injector leakage. These three situations will make the fuel can not be sufficiently mixed with the air in the cylinder, and thus can not be completely combusted. Solution: Check and replace the injector.

5, the injection pump is not working well: injection pump plunger or outlet valve serious wear, injection pump individual or all the plunger or outlet valve serious wear will lead to injection pump pump pressure drop, so that the injector build pressure relative lag, the injection is delayed, after combustion increased, so the diesel engine black smoke. Solution: check the injection pump pressure, repair or replacement.