Car Issues and Fixes

Bad Fuel Pump Relay – Possible Signs and Symptoms

Avatar Adie Tinkle -

Modern vehicles have engines that require a precise amount of fuel to run properly. These engines require a certain amount of fuel at any given moment. The job of the fuel injector pump is to supply a steady flow of electrical current to the fuel pump, which delivers the fuel into the injectors and inside the combustion chamber. The fuel pump relay plays a significant role in getting fuel to your engine for combustion. It provides a fuel pump with enough power to pressurize the fuel system when you turn the key. 

If the fuel pump relay isn’t working, the pump will not work either. This can lead to various significant issues with the vehicle’s reliability and performance. Fortunately, checking for the broken injector pump relay is quite easy. Let’s discuss the prime symptoms of a faulty fuel pump relay. 

Primary Symptoms of Bad Fuel Pump Relay 

There are several reasons why a vehicle’s pump relay can go bad. All of these issues can lead to a problematic driving experience. Therefore, it is important to know the signs of a faulty fuel pump so you can test and replace it when necessary. 

Unable to Start Your Vehicle 

Engine problems are a common sign of a bad fuel pump relay. When you turn on the ignition, it provides the fuel required to create a combustion explosion. A faulty fuel pump relay will not provide the required electrical power to the fuel pump, which in turn will not be able to deliver the required amount of fuel to the engine. 

You can start the engine by turning the motor. If there is no power to activate the fuel pump, no fuel will be sent to the engine. As a result, the vehicle will not start, no matter how long you crank the engine. In some cases, the bad fuel pump can even cause the engine to misfire. 

Rough Acceleration 

A malfunctioning fuel pump reduces the power of the pump and the amount of fuel delivered to the engine. Any issue with the fuel pump relay can impact the fuel flow to the combustion chamber, which can result in issues for your car. Other factors, including clogged fuel filters, can also contribute to difficult acceleration. It is preferable to get your car to a mechanic before making any decisions. 

Engine Stalls and Rough Idling 

A bad pump relay can cause your automobile to stall out or cause rough idling. Inadequate fuel supply can also lead to malfunctioning of the pump relay. In this scenario, you will hear gruff sounds coming from the engine when your automobile is idle.
Similarly, engine stalling can occur as a result of pump relay malfunctioning. In this case, the vehicle will suddenly lose power when you are driving at high speed. You might sense that your engine isn’t operating. The cause behind it can be gasoline supply interruption. 

Check that the Engine Light is On

In some vehicles, the engine computer, also known as the power train module (PCM), monitors the fuel pump relay and its circuit. In the event of a problem, the PCM lights up the check engine light and stores the diagnostic trouble code (DTC).

When the fuel pump relay fails, the car does not receive fuel. This shortage of fuel causes sensors to come on when the required levels of air and fuel mixtures are absent. So, if you see a check engine light on your dashboard, the root cause might be a faulty pump relay. 

Fluctuating Fuel Consumption 

The car’s fuel economy changes as a result of fuel relay malfunctioning. Too much or too little fuel can be injected into the combustion chamber by a malfunctioned relay. It implies that your engine will run rich and lean occasionally. The inconsistent fuel usage in your vehicle is a sign that the fuel pump relay has failed. 

Exhaust System Issues 

In some scenarios, the faulty fuel pump relay gives more fuel than necessary. Only limited fuel is intended to be burned in the engine’s combustion chamber. If additional fuel enters the combustion chamber, it will remain unburned. The car’s exhaust system collects combustion gases. Any extra product, including unburned petrol, can clog your vehicle’s exhaust system. 

Therefore, it is important to check your vehicle’s fuel delivery system. Inspect your pump if you see unburned fuel in the muffler and also experience an exhaust system problem. 

Noiseless Fuel Pump 

The noise from the car’s fuel pump indicates that it is working. The fuel pump plays a critical role in pressurizing the fuel delivery system, particularly when starting a vehicle. Because of that, it pumps fuel at a higher pressure, allowing you to hear it.
If the fuel pump isn’t working correctly, it will operate quietly, and you will not be able to hear it when the automobile is starting or accelerating. If you observe such symptoms, going to an auto repair shop is essential. 

What is the Cause Behind the Failure of the Fuel Pump Relay?

Technically, a short or other electrical malfunction can cause a fuel pump relay to fail. The prime cause of a broken or damaged fuel pump is age. On every click, the relay wears down, and eventually, it gets too much that it either won’t click over again. 

How Can You Test a Fuel Pump Relay?

This is a pretty simple process and involves following the steps: 

  • Park the car on safe and level ground.
  • Turn the ignition key on, and try to listen to the sound of the fuel pump. You can hear a faint buzzing sound.  Don’t worry if you don’t hear any sound. 
  • Locate the fuel relay situated in the engine compartment. After finding it, try to listen to the buzzing or clicking sound again when the key is on. 
  • Disconnect the negative cable from the car’s battery to disable the power sent to the fuel pump and its related circuits. You can manage this task with the help of a socket and wrench. 
  • Remove the fuel relay using needle nose pliers.
  • The next step is to set the multimeter to the battery pins and load it in the pump relay. 
  • Now, send power to the input voltage pin. It should make a beeping sound when you do this. If that’s not the case, your fuel pump relay might be broken or burned out. 

You can test your fuel pump relay after noticing the symptoms. 


Where is the fuel pump relay located in the car?

In most cars, the fuel pump relay is in the fuse box under the dashboard or in the engine compartment. Depending on the type of automobile, the fuel pump relay can be mounted in different places. 

What causes a fuel pump relay to go bad?

There are many reasons why your fuel relay can go bad, the most common of which is an electrical power surge that increases the voltage. The voltage can cause contracts to get burned. These contracts pass current or voltage. In some cases, the signal coil may become shortened due to the high voltage or current of the signal.

How much does the fuel pump replacement cost?

Replacing the fuel pump is a DIY-friendly repair. The fuel pump normally costs about $20 (just for the part). The total cost depends upon various factors, including the vehicle’s age, model, and year. 

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