5 signs of a bad fuel pump relay: How to clean & Replacement cost

Updated Mar 10, 2021 | Same topic: Handy Maintenance Tips

Your car is having difficulty starting? Check this out.

What is a fuel pump & what does it do?

Location

There are different locations for a fuel pump relay depending on the manufacturer. You could find your car’s fuel pump relay in the engine bay alongside other fuses. You could also find it on your car’s firewall near the brake and gas pedal hidden under a plastic panel. If you can’t find it, look it up or consult your manufacturer to make sure that you got the right relay.

Function

The main function of a fuel pump relay is to supply the right amount of current to the fuel pump from the battery to pump fuel to the engine. Once you turn your key to ignition, you will hear a low sound noise which means that your fuel pump is priming the engine with the help of a fuel pump relay.

With that being said, it is ideal to wait for a few seconds before cranking your car’s starter motor to avoid problems with starting the engine. The fuel pump relay shuts off once your engine is running and the fuel pump is powered by the oil pressure sending unit. It will be engaged again after switching the ignition off to help power down the fuel pump.

A removed fuel pump relay

A fuel pump relay is essential in running your car's engine [Photo: Wikihow]

5 symptoms of a bad fuel pump relay

Symptom #1: No fuel pump noise

As said earlier, you will hear a whining noise or buzz when you are about to start your car. The noise comes from the fuel pump sending fuel to the engine powered by the fuel pump relay. Waiting for at least two seconds before cranking the starter motor would be great to make sure that the engine is primed optimally.

If you don’t hear that there is no noise before starting the engine, then your fuel pump relay might not be sending current to the fuel pump for engine priming. You should also be aware of the condition of your fuel pump as it could also be the reason why it doesn’t make a whining or buzz sound when turning the ignition key on.

>>> Related: 10 bad car noises Filipino drivers should look out for

Symptom #2: Engine not starting

The engine requires fuel from the fuel tank to start cranking. If your car has a bad fuel pump relay, then the fuel pump will not supply the adequate engine to start the engine.

However, the engine not starting is one of the most common problems caused by various reasons outside a bad fuel pump relay. Some of which include a faulty battery, cold weather, and bad fuel injectors. As such, consult your mechanic about what could be the reason before replacing your fuel pump relay.

Symptom #3: Check engine light

One of the easiest ways to help you tell whether your fuel pump relay is not working is to check whether the engine light is illuminated. The engine control unit is sensing that the reading of the power of the fuel pump relay is below the appropriate number for an ideal engine operation, hence illuminating the check engine light.

Checking the engine light might be an easy way for you to determine the condition of your fuel pump relay, but the illumination could also mean a lot of other problems in your car. Consult your automotive shop where the problem is coming from so you can turn the check engine light off.

Check engine light illuminated

An illuminated check engine light means you need to get your car checked

Symptom #4: Loss of power

The battery may be the supplier of power to your car, but the fuel is the energy source to keep it charging through the alternator. Without a functioning fuel injection system, your car will lose power for both the electronic and mechanical components which cause your car to slow down.

A car must maintain a certain amount of RPM to keep itself running. Too much loss of power will also cause your car’s engine to stall. As such, it is important to always check your fuel pump relay so your fuel pump will continue sending fuel to the engine operating.

Symptom #5: Age

A fuel pump relay is meant to last for a very long time since it is not exposed to high temperature or pressure operations in your car. However, a fuel pump relay can still go bad due to various reasons such as wear and oxidation. Your car’s mileage can help you determine whether your fuel pump relay needs replacing.

On average, a fuel pump relay will last for 160,000 km to 300,000 km. If the car is daily driven, the said mileages could mean that the car is used for around eight to 15 years already. If your car reaches this point, then it could mean that you need to replace it so your fuel pump will work properly.

Two fuel pumps

An illuminated check engine light means you need to get your car checked

>>> Related: 7 Fuel Pump Problems That Tell You It's Time For A Replacement

How to clean a fuel pump relay

If your fuel pump relay is located in the engine bay, then dust and dirt can be accumulated in the said part. As we all know, electrical components must always be cleaned so the parts will be contacted thoroughly. A dirty fuel pump relay might cause a loss in power which results in difficulty in starting your car.

To clean your fuel pump relay, you can use a blower to dust off the particles. Do not use water to clean your fuel pump relay since it is an electrical component. Instead, you can use a small amount of ethanol just to completely wipe off dust or dirt. Let it dry for a few seconds before putting it back to the fuse box.

A car's fuse box

Consult your manufacturer to make sure where your fuel pump relay is located [Photo: CarCareTotal]

How much does it cost to replace a fuel pump relay?

A fuel pump relay is not as expensive as other major parts so replacing it shouldn’t be much of a problem. You can get a fuel pump relay in the Philippines for around Php 750 to Php 2,000, depending on the model you are driving.

If you are also paying for the labor cost, then the replacement cost could total to around Php 1,500 to Php 4,000. It is recommended to make sure that your fuel pump relay is the part that needs to be replaced so you can avoid paying for a new fuel pump which can cost around Php 10,000 for OEM.

A car's push-start switch

In case you won't start, consider checking the fuel pump relay

FAQs about fuel pump relay

Q: How long does a fuel pump relay last?

A fuel pump relay should last long enough before you replace your car with a new one.

Q: What is a fuel pump?

A fuel pump delivers fuel to the injectors from the fuel tank.

Q: How much is fuel pump relay in the Philippines?

Fuel pump relays are available online with a price that ranges from Php 750 to Php 2,000.

Q: Where does the fuel pump relay get its current?

The battery supplies power to the fuel pump relay used for starting the engine and after shutting it off.

Q: What happens if I have a bad fuel pump relay?

Your car could experience a loss of power since your fuel pump is not supplying enough fuel to the engine.

Here at Philkotse.com, we value your interest in the automotive industry. Visit our website to find out more.

Rex Sanchez

Rex Sanchez

Author

Rex started off his career in the aviation industry before entering Philkotse as a staff writer. Two things excite him the most: first is staying up to speed with the latest news in the industry that uses engines as their heart and soul. The second is imparting them in a well-detailed manner. His passion for anything with wheels started when he was young – from Tamiyas to family-friendly sedans, and anything in between.

Someday, Rex only wishes to drive on random highways with friends in a third-gen Mitsubishi Delica with aftermarket sunroofs, if he couldn’t get the Starwagon Super Exceed edition.

View more