When the vacuum degree in the intake manifold decreases, the vacuum gasoline pressure regulator reduces the gasoline pressure.

ECU controls the fuel injection quantity according to the fuel injection time; When the difference between the internal pressure and the external pressure of the injector is different, the injection quantity at the same time will be different; In order to accurately control the fuel injection quantity, an oil pressure regulator is set to adjust the gasoline pressure in real time, so that the pressure difference between the inside and outside of the injector remains constant under different working conditions.

When the vacuum degree in the manifold decreases, the pressure difference between the inside and outside of the injector decreases, the injection quantity at the same injection time decreases and the air-fuel ratio increases. In order to make the engine run at a normal air-fuel ratio, the pressure regulator increases the gasoline pressure, so that the pressure difference between the inside and outside of the injector increases to a normal value.

The working principle of the fuel pressure regulator is as follows:

The oil pressure is coordinated by the spring and the vacuum degree of the air chamber. When the oil pressure is higher than the standard value, the high-pressure fuel pushes the diaphragm upward, the ball valve opens, and the excess fuel flows back to the oil tank through the oil return pipe. When the pressure is lower than the standard value, the spring will compress the diaphragm, close the ball valve and stop oil return.

ECU can accurately control the fuel injection quantity by controlling the fuel injection time.