Test static fuel pressure in the fuel system

(1) Use a short wire to connect the two detection jacks of the electric fuel pump ( generally on the electric control car have two detection jacks. If it cannot be found, it can supply power to the electric fuel pump directly ).

(2) Turn on the ignition switch (but do not start the engine) and let the electric fuel pump run.

(3) Measure the fuel pressure, the normal fuel pressure should be about 300kPa. If the fuel pressure is too high, check the fuel pressure regulator. If the fuel pressure is too low, check the electric fuel pump, fuel filter and fuel pressure regulator.

(4) Turn off the ignition switch and unplug the short wiring of detection jacks in the electric fuel pump.

Test the holding pressure in the fuel system 

After measuring the static fuel pressure for 5min, observe the value of the fuel pressure gauge. At this time, the pressure is called the fuel system fuel holding pressure. Its normal value should be no less than 147kPa. If the fuel pressure is too low, check the  holding pressure of the electric fuel pump, the holding pressure of the fuel pressure regulator and the leakage of the fuel injector.

Test fuel pressure during engine operation

(1) Start the engine, let the engine run at idle, and measure the fuel pressure at this time.

(2) Slowly open the throttle valve (press down the accelerator pedal) to measure the fuel pressure when the throttle valve is close to full open.

(3) Remove the vacuum hose on the oil pressure regulator and stop it by hand, and let the engine run at idle and measure the fuel pressure at this time.

The pressure should be basically equal to the fuel pressure when the throttle valve is fully open. If the measured fuel pressure is too high, check the oil pressure regulator and its vacuum hose. If the measured oil pressure is too low, check the electric fuel pump, fuel filter and fuel pressure regulator.

Test electric fuel pump’s maximum pressure and holding pressure 

(1) Release pressure in the fuel system.

(2) Remove the battery negative (ground).

(3) Connect the fuel pressure gauge on the fuel supply line and plug the fuel outlet.

(4) Connected to the battery negative (ground).

(5) Use a wire to connect the two detection jacks of the electric fuel pump.

(6) Turn on the ignition switch about 10 seconds (do not start the engine). Make the electric fuel pump work and read the pressure of the fuel pressure gauge. This pressure is called the maximum pressure of the electric fuel pump. Its normal value should be 200 ~ 300kPa higher than the fuel pressure of the engine running, usually up to 490 ~ 640kPa. If not up to standard value, you should replace the electric fuel pump.

(7) Turn off the ignition switch and observe the pressure of the oil pressure gauge after 5min. At this time, the pressure is called the  holding pressure of the electric fuel pump, whose normal value should be higher than 340kPa. If not up to standard value, should replace the electric gasoline pump.