The mixture in Yue Feng is too thin. What happened?

The lean mixture is mostly due to the low oil pressure of the fuel pump, unclean fuel injector or control circuit failure, and poor intake pressure sensor signal can also lead to lean mixture.

When the mixture is too thin, the combustion speed of the fuel decreases, and when the piston moves to the bottom dead center (referring to a four-stroke engine, that is, when the space volume of the combustion chamber increases gradually), a part of the mixture will be burned. In severe cases, the combustion process will even be postponed until the intake stroke of the next cycle, so that the flame remaining in the cylinder will ignite the mixture in the intake pipe and the carburetor oil outlet cavity through the open intake valve, forming backfire (also known as carburetor backfire) and producing a slap sound. Not only does this part of the heat released by the combustion of mixed gas become relatively less mechanical work, but also the heat lost to cooling water or radiator through the cylinder wall is relatively increased. Therefore, if the mixture is too thin, the engine will overheat and the output power will decrease. If the mixture is too thin, its idle speed will be high, and it is difficult to reduce the engine speed to idle speed in a short time when accelerating back to the throttle. At this time, when the spark plug is removed, it will be found that the electrode color is white, and it can be confirmed that the combustible mixture is too thin.

In this case, if it is a computer adjustment problem, then repair the engine computer. If it is mechanical, the engine must be taken apart for repair.