Common faults and troubleshooting of electric fuel pump

Update:04 Jan 2020
Summary:

(1) Fuel pump does not rotate If the electric fuel pump […]

(1) Fuel pump does not rotate
If the electric fuel pump does not run, it means that the fuel pump or the wiring is faulty, you can check it according to the following steps:
a. Check if the power plug of the fuel pump is loose and the connecting wires are not disconnected. The method is: unplug the fuel pump, connect the test light to the two terminals of the plug, and turn on the wire switch. If the test light is on, the power supply voltage is normal, and the fuel pump is faulty; if the test light is off, the line If there is a fault, you should find it according to the circuit diagram. [2]
b. Check the fuse, main relay, power-off relay and their connections. You can turn off the ignition switch, open the fuse box cover on the left side of the instrument panel, pull out the fuse of the fuel pump, and connect the two ends of the fuse holder with a wire with a switch. Check if you can hear the sound of the fuel pump running. If the fuel pump still does not rotate, the fuse or relay is open
c. If the above inspection is normal, but the fuel pump still does not rotate, it may be a problem with the fuel pump switch. In the L-type electronically controlled fuel injection system, the fuel pump switch is located in the air flow meter.In addition to the ignition switch, the electric fuel pump is also controlled by the air flow meter. Only when the engine starts and air flows in the air flow meter Only when the electric fuel pump works. Therefore, when checking the fuel pump of the L-type electronically controlled fuel injection system, the fuel pump inspection switch in the control circuit should be pressed. [2]
2.The fuel pump can rotate but does not produce oil
The main reasons that the fuel pump can rotate but does not produce oil are:
a. The fuel filter of the fuel pump is blocked. Take out the fuel pump from the fuel tank for inspection, and see that the 3 filters of the fuel pump are almost blocked by black powdery impurities. Put it in gasoline to clean it, and then blow the filter and the oil passage with compressed air, and troubleshoot.
b. The fuel pump check valve is stuck in the closed position, the fuel inlet is blocked, and the pumped fuel cannot enter the fuel pipe.
c. The spring of the pressure relief valve (or safety valve) is broken, the valve is stuck in the open position, and the pumped fuel flows back to the fuel tank through the pressure relief valve (or safety valve).
d. The fuel pump impeller and pump casing are severely worn. In this case, only the fuel pump must be replaced. [2]
3.The pump oil pressure is too low
If the oil pressure is too low, the amount of fuel injected by the injector will be reduced, resulting in difficulty in starting the engine and reduced power. The judgment method is: insert an oil pressure gauge in the oil circuit to stabilize the engine speed at 3 000 r / min. If the pointer of the oil pressure gauge swings rapidly between 220 and 300 kPa, it indicates that the fuel pump pressure is normal; The pointer of the pressure gauge pauses slightly at a certain position, indicating that the fuel pump is worn. You can also use a pressure gauge to test the fuel pump pressure of the fuel pump, pinch the oil return hose of the fuel pressure regulator with your hands, and if the oil pressure is still too low at this time, it means that the fuel pump has insufficient fuel supply, and the reason is that the fuel pump If the pressure relief valve (or safety valve) is leaking oil, the oil inlet filter is blocked, the impeller and the pump casing are worn, etc., the fuel pump should be replaced. The fuel pressure regulator should be inspected for damage.