Common Signs and Symptoms of Bad Fuel Pump Relay | How Do You Test A Fuel Pump Relay?

Symptoms of Bad Fuel Pump Relay

Common Signs and Symptoms of Bad Fuel Pump Relay

A fuel pump relay is a vital component in a vehicle’s fuel delivery system, responsible for regulating the flow of electrical current to the fuel pump. When this relay malfunctions, it can lead to a variety of noticeable symptoms that can hinder the performance of your vehicle.

In this article, we will discuss some of the common signs and symptoms of a bad fuel pump relay, allowing you to quickly identify and address any issues before they escalate into costly repairs. Knowing the warning signs of a failing fuel pump relay is crucial for every car owner, so read on to learn more.

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Symptoms of Bad Fuel Pump Relay

The fuel pump relay is an essential component of a vehicle’s fuel system. It is responsible for controlling the fuel pump, which supplies fuel to the engine. A faulty fuel pump relay can cause various symptoms that can affect the performance of the vehicle.

Here are some common symptoms of a bad fuel pump relay:

#1. Engine Stalling or Not Starting

One of the most common symptoms of a bad fuel pump relay is the engine stalling or not starting at all. This is because the fuel pump relay is responsible for supplying power to the fuel pump, and if it fails, the fuel pump will not be able to provide fuel to the engine.

#2. Sputtering or Hesitating Engine

If the fuel pump relay is faulty, it may not provide a consistent flow of fuel to the engine. This can cause the engine to sputter or hesitate, especially at high speeds or when accelerating.

#3. Difficulty Starting the Engine

A bad fuel pump relay can also make it difficult to start the engine. This is because the fuel pump relay may not provide enough power to the fuel pump, which in turn, cannot supply enough fuel to the engine for ignition.

#4. Engine Misfires

A faulty fuel pump relay can also cause the engine to misfire. This happens when the fuel pump relay does not provide enough fuel to the engine for combustion, resulting in a misfire.

#5. Decreased Fuel Efficiency

The fuel pump relay is responsible for providing fuel to the engine in the right amount. If the relay is faulty, it may not supply enough fuel, causing the vehicle’s fuel efficiency to decrease.

#6. Loud Whining Noise from the Fuel Tank:

A failing fuel pump relay can make a loud whining noise from the fuel tank, which may be audible even when the vehicle is running. This noise is a result of a struggling fuel pump trying to supply fuel to the engine.

#7. Check Engine Light

In some cases, a bad fuel pump relay may trigger the check engine light to come on. This is because the engine’s sensors may detect a problem with the fuel system, which can be caused by a malfunctioning fuel pump relay.

If you experience any of these symptoms, it is recommended to have your vehicle inspected by a mechanic. Ignoring a faulty fuel pump relay can lead to further damage and potentially leave you stranded on the road.

A professional mechanic will be able to diagnose the issue and replace the faulty component, restoring the proper functioning of your vehicle.

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How Do You Test A Fuel Pump Relay?

A fuel pump relay is an integral component of a vehicle’s fuel delivery system. It controls the flow of electricity to the fuel pump, which is responsible for delivering fuel from the gas tank to the engine. If the fuel pump relay fails, the fuel pump will not receive power, and the vehicle will not start or run.

This is why regular testing of the fuel pump relay is vital to ensure the proper functioning of a vehicle. In this article, we will discuss the steps involved in testing a fuel pump relay.

Materials needed:

  • Multimeter
  • Wiring diagram for the specific vehicle model and year.
  • Battery terminal tool or 10mm wrench.
  • 12V power supply.

Steps for testing a fuel pump relay:

Step 1: Locate the Fuel Pump Relay

The fuel pump relay is usually placed in the power distribution box under the hood of the vehicle. It is also sometimes located under the dash near the steering column. The owner’s manual or a repair manual can help to pinpoint the exact location of the relay.

Step 2: Understand the Wiring Diagram

The wiring diagram for the specific vehicle should be referred to in order to know the pin arrangement of the fuel pump relay. A wiring diagram will show the power and ground wire connections, the control wire, and the load wire.

Step 3: Remove the Fuel Pump Relay

Before removing the relay, disconnect the negative terminal of the battery to avoid any accidents. Use a battery terminal tool or a 10mm wrench to remove the fuel pump relay.

Step 4: Test the Relay with a Multimeter

Set the multimeter to Ohms on the 200 scale. Connect the positive lead of the multimeter to the control wire pin labeled “C” on the fuel pump relay and the negative lead to the ground pin labeled “G” or “E” on the relay. A reading of 75 ohms or less is considered normal. If the reading is higher, the relay is faulty.

Step 5: Test the Relay Coil

Using the multimeter, set it to “continuity” or the “diode test” mode. Now connect one of the leads to the positive terminal on the battery and the other to the ground pin on the relay. The multimeter should beep, and this indicates that the coil is good. A lack of beep means the coil is faulty.

Step 6: Test the Connections on the Relay

Connect the positive lead of the multimeter to pin “B” on the relay and the negative lead to pin “D”. Next, connect the positive lead to pin “A” and the negative lead to pin “C”. Both readings should be infinite. Any reading besides infinite means the relay is faulty.

Step 7: Test the Relay with a 12v Power Supply

Connect the 12V power supply to pins “A” and “B” on the relay. Then connect the multimeter leads to pins “D” and “E”. The multimeter should read 12V or close to it. If there is no voltage or a significant difference in voltage, the relay is faulty.

Step 8: Replace the Fuel Pump Relay

If any of the above steps shows that the relay is faulty, it needs to be replaced. A new relay can be purchased from a local auto parts store or online. To install the new relay, reverse the steps followed to remove it.

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Conclusion

In conclusion, a bad fuel pump relay can have a significant impact on the performance and functionality of a vehicle. It is important to be aware of the common signs and symptoms of a faulty fuel pump relay, such as engine stalling, difficulty starting the vehicle, and a lack of power. Ignoring these signs can lead to further damage and potentially leave you stranded on the side of the road.

If you suspect that your fuel pump relay may be malfunctioning, it is essential to have it inspected and replaced by a professional mechanic. By addressing this issue promptly, you can avoid costly repairs and ensure your vehicle runs smoothly. Remember to always pay attention to any unusual behavior from your car and address it promptly to maintain its optimal performance.


Frequently Asked Questions (FAQ)

What Is a Fuel Pump Relay?

A fuel pump relay is a critical component in a vehicle’s fuel delivery system. It regulates the flow of electrical current to the fuel pump, ensuring the proper supply of fuel to the engine.

What Are Common Symptoms of a Bad Fuel Pump Relay?

Common symptoms include engine stalling or not starting, sputtering or hesitating engine, difficulty starting the engine, engine misfires, decreased fuel efficiency, a loud whining noise from the fuel tank, and the check engine light turning on.

How Does a Bad Fuel Pump Relay Affect Engine Starting?

A malfunctioning fuel pump relay can prevent the engine from starting as it fails to supply power to the fuel pump, which in turn cannot provide fuel to the engine.

Can a Faulty Fuel Pump Relay Cause Engine Misfires?

Yes, if the relay does not provide enough fuel for combustion, it can lead to engine misfires.

What Impact Does a Bad Fuel Pump Relay Have on Fuel Efficiency?

A faulty relay can decrease fuel efficiency by not supplying the correct amount of fuel to the engine.

Why Might a Bad Fuel Pump Relay Produce a Whining Noise?

This noise comes from the fuel tank, caused by the struggling fuel pump trying to supply fuel to the engine.

How Can You Test a Fuel Pump Relay?

Testing involves locating the relay, understanding the wiring diagram, removing the relay, and using a multimeter to test for continuity, resistance, and voltage supply. Specific steps include testing the relay with a multimeter, testing the relay coil, testing connections, and using a 12V power supply.

What Materials Are Needed for Testing a Fuel Pump Relay?

You’ll need a multimeter, the vehicle’s wiring diagram, a battery terminal tool or 10mm wrench, and a 12V power supply.

What Should You Do If the Fuel Pump Relay Is Faulty?

If testing indicates a faulty relay, it should be replaced with a new one, available at auto parts stores or online.

Why Is It Important to Address a Bad Fuel Pump Relay Promptly?

Ignoring symptoms of a bad relay can lead to further damage, costly repairs, and the risk of being stranded.


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