Faulty Fuel Pump Relay (FPR) - Signs and Symptoms

The fuel pump relay (FPR) is a small electrical component that controls the fuel pump's power supply. Fuel pumps typically draw an electric current of 3-8 amps. Therefore, the FPR deals with a large amount of heat. Most engine start-up problems can be linked to poor performance or failure of the FPR. You could confirm it by finding the following signs and symptoms.

Engine cranks but refuses to start

When you turn on the ignition, you will hear your engine cranking, but the vehicle will not start. This indicates that there is an issue with the fuel delivery system and is most likely due to a bad FPR. As it supplies the required power to switch on the fuel pump, any malfunction in FPR results in lack of power supplied to it, which results in failure of fuel supply, which in turn prevents the vehicle from starting.

Engine stops suddenly after starting

Sometimes the engine may start normally, but after a little while, it stops suddenly. For the first few seconds, the ECU supplies power to the FPR. This helps fuel pump to pressurize the fuel system, and makes the car start. But later, due to the faulty operation of FPR, the fuel pump will not receive the required power, which makes the vehicle gradually slow down and stop abruptly.

Delay in starting

Delay in starting could also be a sign of faulty FPR. If you are persistently noticing the same issue, it's a probable sign of the problem.

Vehicle won't start when hot
When the engine is cool, the car starts normally. After a 30-40 minute drive, once the engine becomes hot, it stops working. Once the engine cools down, the car will start normally. This is because at operating temperatures, the FPR sequence stops working.

Loses power while on drive
Another sign is that the car begins to slow down without your involvement. Again, the ECU is unable to maintain an energized FPR. So, if you are experiencing it more than a couple of times better, it sensible to take it to your mechanic before your vehicle stops working altogether.

No start-up noise

You might be aware of the typical noise emitted by your vehicle when you turn on your ignition. When there is any issue, you are unlikely to hear such a noise.

Now that you came to know the signs and symptoms of a failing FPR, identify and get them fixed before they cause damage to all the critical components in the fuel delivery system.

Airtex Products is the leading aftermarket supplier of mechanical and electric fuel pumps. For over 50 years, the Airtex brand has been the benchmark of fuel delivery components for leading companies in the automotive aftermarket. If you are searching for a fuel pump, consider Airtex as Airtex fuel delivery system has exceptional quality that meets or exceeds OE design specifications and ISO standards.