Symptoms and Inspection Methods of Fuel Pump Relay Failure

by MOU YONG HONG on December 01, 2021

The fuel pump relay is an electronic component that will be found in most vehicles equipped with combustion engines. it's usually located within the fuse box up the engine compartment and used because the main electronic switch to regulate the facility supply of the fuel pump. The fuel pump relay is typically controlled by the ignition or powertrain control module, and when it's switched on, it'll provide current to the fuel pump to form its works. Since the fuel pump relay controls the facility supply of the fuel pump, any failure may cause problems with the fuel pump, which can cause problems with the driving performance of the vehicle. Normally, a malfunctioning or malfunctioning fuel pump relay produces symptoms, and these alarms may warn the driving force.


1. Engine stall

One of the primary symptoms of a drag with the fuel pump relay may be a sudden engine stall. If there's a drag with the fuel pump relay while the vehicle is running, it'll stop the facility to the fuel pump, which can cause the engine to stall. A relay failure may cause the vehicle to restart later, while a totally failed relay won't.

2. The engine can't be started

Another symptom of a fuel pump relay failure is that the engine can't be started. If the fuel pump relay fails, the fuel pump will remain de-energized. When the key's turned, the engine should start, but thanks to lack of oil, the engine won't start. This symptom can also be caused by various other problems, so it's strongly recommended to properly diagnose the vehicle.

3. No noise from the fuel pump

Another symptom that will indicate a drag with the fuel pump relay is that there's no sound from the fuel pump when the key's turned on. Most fuel pumps emit a low-volume hum or whine, which may be heard from inside the car if you listen carefully, or from outside the car near the fuel tank. If the fuel pump relay fails, it'll stop the facility to the fuel pump, which can make it inoperable, so it remains silent when the switch is turned on.

How to check whether the fuel pump relay is working:

1. One person activates the switchand therefore the other person holds the hose a part of the gas line. If the hose doesn't feel a pulsation when starting, the rationale for the failure to start out is that the fuel pump relay and its circuit.

2. One person opens the fuel tank cap and listens to the sound of the fuel pump pumping, and therefore the other person activates the switch, and you'll hear the sound of pumping oil for two seconds at the fuel tank cap. If you cannot hear the sound of pumping oil, the fault lies within the fuel pump relay and its circuit.

Should specialize in checking whether the fuel pump relay is short-circuited to the positive electrode, and therefore the connection circuit between the control unit and the fuel pump. If the switch is turned on and therefore the fuel pump runs continuously, it's going to be that the fuel pump relay is shorted to the ground.

Although the fuel pump relay may be a very simple component, it plays a really important role within the normal operation of the vehicle. If your vehicle shows any of the above symptoms, or if there's a drag together with your own fuel pump relay, please have a knowledgeable technician inspect the vehicle to work out whether the component should get replaced.


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