Fuel Pump Is Not Working (Causes And Fixes) (2024)

Updated on January 12, 2023

If you notice your car suddenly doesn’t want to start or it began randomly stalling earlier, chances are the fuel pump is failing. However, if there were no prior symptoms and you don’t hear that distinct buzzing sound in the trunk when you turn the key, it’s likely some other related component. Luckily, each potential culprit is pretty easy to inspect and test, but before we go into more detail, here is what those are.

If you notice the fuel pump is not working, chances are the fuel pump itself has failed. However, it could also be a blown fuel pump fuse, a burnt-out relay, wiring damage, or a corroded fuse box. And in some rare cases, it could be that the fuel cut-off switch is triggered. So, before you replace a healthy fuel pump, it’s a good idea to test each of these potential causes first, so read on to learn how.

Blown Fuel Pump Fuse

There doesn’t have to be a reason why a particular fuse burns out; it’s just something that happens from time to time. And that’s the case with the fuel pump fuse as well. Now, the easiest way to check if a fuse is good is to perform a visual inspection.

But before that, you have to find the fuse first, and the easiest way to do it is to check your owner’s manual. In the manual, you will find a section covering fuses with a complete list and their functions. Luckily, the fuel pump doesn’t share a fuse with any other components, so it will be easy to find.

Once you find the fuse, pull it out and check if the fusing element in the middle is broken. If you find that it’s broken, replace the fuse with a correct amperage one, and you are good to go. Otherwise, let’s continue our investigation.

Corroded Fuse Box

If the fuel pump fuse is all in one piece, it could still mean it’s not getting any power. The main reason for that is a corroded fuse box. However, the fuse box will only corrode if it’s in the engine bay, which, in most cases, it’s not. In most cars, the fuse box is in the interior, and the relay box is in the engine bay, but we will cover the relay box a little later. So, if you find your fuel pump fuse in the engine bay, you can read how to test it here; if not, skip to the corroded relay box part. And now, here is how to check if the fuel pump fuse is getting power.

How to Test and Clean a Fuse Box

To complete this task successfully, you’ll need a multimeter.

1. Find and remove the fuel pump fuse
2. Set your multimeter to 12V DC
3. Turn the ignition on but don’t start the engine
4. Place the back probe on a bare metal chassis part of the engine
5. Place the red probe in one of the fuse terminals and then in the second one.
6. If the multimeter reads around 12V in any of the two terminals, the fuse box is good.
7. If not, turn the ignition off and use some rust remover spray and a wire tube brush to clean it thoroughly.
8. Then, let everything dry for five to ten minutes and test it again.
9. If that doesn’t work, you will likely have to remove the entire fuse box and inspect it.

Burnt Out Fuel Pump Relay

Since the fuel pump requires a lot of power and current, the relay is in place to help prevent wires from overheating. But since the relay is also a mechanical component with moving parts, it does have a limited lifespan. And needless to say, once it fails, no power will go to the fuel pump. So, to check the relay, you first have to find it, and you can do that using the owner’s manual.

The fuel pump relay is typically located in the engine bay relay box, and you can find its diagram in the owner’s manual, just like you do for the fuse box. Now, once you find the relay, it’s fairly easy to check if it’s working. You can have someone turn the ignition on without starting the engine. While the second person is turning the ignition on, you should put your ear close to the relay and notice if you hear any clicking sounds.

If you do, the relay is good; if not, it’s probably failed. Now, if you are unhappy with this method, you can always remove it and take the plastic cover off to inspect it. A bad relay will always show burning signs and worn metal components. And if it turns out the relay is faulty, replace it with the correct one, and you are good to go.

However, if while performing a visual inspection, the relay looks brand new but there is no clicking, it might not be getting any power. Luckily, we have already covered the case where the fuel pump relay isn’t getting power, so you can skip to this article to see all the causes and fixes for that.

Triggered Fuel Cut-Off Switch

The fuel cut-off switch is a safety feature that all vehicles in the past 20 years and longer have had. Its main purpose is to cut off the fuel supply to the engine in case of a crash so that the possibility of fire is minimized. The way it works is vibrations and impacts trigger it, and once it’s triggered, it cuts off power to the fuel pump.

However, the system is not foolproof and can get triggered when you hit a big pothole or even if you accidentally hit it with something. That usually happens if it’s located in the trunk, but you will sometimes find it in the glove box or behind it.

The switch itself is a small black box with a red button on top. When the switch is triggered, the button pops up, and to fix it, all you have to do is push the button back down. And to find the switch, you can check your owner’s manual.

Faulty Fuel Pump Wiring

If everything checks out so far, the fuse, fuse box, relay, etc. The last thing left to check before the fuel pump is the wiring. The easiest way to do this is to access the fuel pump and test it with a multimeter. Alternatively, you can find a wiring diagram for your car and locate the last wiring connector before the fuel pump. You can also trace the wires coming from the fuel tank and find the first connector in line.

If you find a fuel pump connector, disconnect it and turn the ignition on. After that, set your multimeter to 12V DC, place the black probe on a bare metal chassis part, and test each connector pin with the red probe. While doing that, check if the multimeter shows 12V at any time; if it does, the wiring is good. Otherwise, there is likely a break somewhere, and you will have to inspect the whole harness.

However, if you can access the fuel pump, even better; again, place the black probe on a bare metal piece, and test the fuel pump terminals with the red probe. If the multimeter shows 12 volts on any of the terminals, it’s all good. Otherwise, the fuel pump has failed.

Fuel Pump Failure

All the testing prior to the fuel pump wiring was essentially troubleshooting why the fuel pump wasn’t getting any power. And considering that after the wiring test, we now know the fuel pump is getting power, the only thing left is to replace it. The fuel pump is a mechanical component that will fail over time either because it’s worn out or due to an electrical failure.

In terms of cost, a replacement fuel pump is usually around $35 to $70, while a high-quality or OEM one is between $100 and $150. As for labor, you can expect to pay for around 0.5 to 1.5 hours. However, you can also replace the fuel pump fairly easily at home with some basic tools. But before you do, ensure your vehicle has a fuel tank access point under the rear seats or in the trunk. Otherwise, this job is better left to professionals.

How to Replace a Fuel Pump

1. Locate the fuel tank access point and remove the plastic cover over it. If it’s under the rear seats, you can easily remove them by pulling them up, as there are no bolts holding them down.
2. Now, remove all the hoses and the electrical connector.
3. Now you have to unfasten the big plastic ring holding the fuel pump. You can do that with a flat screwdriver and a hammer or appropriately sized pliers. But before you do, note the arrow on the cove and mark it, so you install it back in the same position.
4. Once the ring is off, pull the fuel pump assembly out. The assembly likely also holds the fuel level sender.
5. Now, you have to remove the fuel pump from the assembly. Sometimes it’s held with plastic tabs/clips, and sometimes with a clamp.
6. Then, replace it with a new one and install everything in reverse order.
7. Also, make sure you attach all the hoses correctly, and again, note the arrow on the top of the fuel pump/fuel level sender assembly and position it correctly.

If you don’t know how to replace a fuel pump, watching this video will help you out.

What Does the Fuel Pump Do?

The fuel pump we have been discussing pushes fuel up to the fuel rail and injectors. So, its only purpose is to transport fuel. High-pressure fuel pumps, however, have the task of atomizing the fuel entering the combustion chamber. But those pumps are only found on direct injection engines and are largely unrelated to the one we are talking about.

What Are the Signs of a Failing Fuel Pump?

The main signs of a failing fuel pump are high-pitched buzzing coming from the fuel tank, inability to start the engine, and engine stalling while driving or idling. Some less common signs are acceleration surges, poor fuel economy, engine performance, and a rough idle.

Is It Worth Fixing a Fuel Pump?

No, it’s not worth fixing a fuel pump. First of all, you have to remove the fuel pump and then disassemble it, but keep in mind that the fuel pump is sealed. Then, you have to source parts which means buying a used pump because those parts are not available. And lastly, you would have to be highly skilled to pull the whole job off. So at the of the day, it makes much more economic sense to just buy a new one.

Can You Drive a Car Without a Fuel Pump?

No, you cannot drive a car without a fuel pump. Driving without a fuel pump is something you can pull off with motorcycles where the fuel tank sits above the engine, so the fuel naturally falls down. However, that’s not possible with cars because the tank is lower than the engine, and it’s further away from the engine.

How Do Fuel Pumps Get Damaged?

Fuel pumps most often get damaged by fuel starvation or contamination. Fuel starvation happens each time you run out of fuel and keep trying to start the engine. On the other hand, fuel is always a little contaminated, but the problem becomes serious if you fail to replace your fuel filter regularly or drive the car with low fuel for a long time. Other than that, the fuel pump fails because of natural wear and tear.

Can a Fuel Pump Fail Suddenly?

Yes, a fuel pump can fail suddenly. As a matter of fact, the vast majority of fuel pump failures happen suddenly and unpredictably without any telltale signs. And in the best-case scenario, the car might fail to start once or twice, giving you a hint.

What Does a Fuel Pump Sound Like?

A fuel pump in normal conditions makes a subtle low-pitched hum for about five seconds when you turn the ignition on. However, if the pump is fuel starved, you will hear a loud, high-pitched buzz that’s pretty difficult to miss. Other than that, you might hear slight grinding and crushing if the fuel pump gears are failing.

Conclusion

Ultimately, if your fuel pump isn’t working, there is not much point in chasing the reasons why it failed. Also, the only solution, in that case, is to replace it with a new one. However, there are several other potential causes of why the fuel pump isn’t working, and all are fairly easy to test.

The first reason is a blown fuel pump fuse, and while you are there, use a multimeter to test the fuse box too. Secondly, check the fuel pump relay and do the same test as with the fuse box. and lastly, you might be looking at a triggered fuel cut-off switch or faulty wiring. And hopefully, our guides on how to check each and fix them were helpful.

For more related fuel pump topics, here are our other posts:

How To Test A Fuel Pump Without A Pressure Gauge

5 Common Problems After Changing a Fuel Pump

How To Start A Car With A Bad Fuel Pump