Common Problems After Changing Fuel Pump

During your routine maintenance or some signs show that your fuel pump has some issues, and you decide to replace it. However, even after replacing it with a new fuel pump, the problems do not go away or worsen. So, what are such problems and their solutions to keep the vehicle driving as it should?

Most people may experience difficulty with the engine starting. Just because it is a new fuel pump, that should be enough indicator of a problem. Also, you may experience inconsistent engine revs, the engine may stall, have a rough idle, and so much more, depending on the severity of the problem.

When there is a problem with your fuel pump, your vehicle will not drive correctly. This is mostly because there is not enough fuel pressure reaching the engine. When the engine is starved, it will stall or not run. So, a proper diagnosis is necessary to determine what could be the issue.

We help you understand why this is happening and the solutions to consider. Also, we discuss the steps of troubleshooting the new fuel pump and how to avoid mistakes while installing a new fuel pump.

Problems and Solutions After Changing Fuel Pump

Understanding these problems with their solutions should help make the vehicle drivable if it has an issue after changing the fuel pump. Here are some of the problems you may experience and their solutions.

1. Engine has difficulty starting

You may notice that even while the engine cranks, it does not start. It could be that the new engine pump is not building up enough fuel pressure to get the fuel to the engine. It could also be that there is no fuel at all getting to the engine.

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It is best to measure the fuel pressure using a fuel pressure gauge to understand how much pressure the pump is generating.

A normal fuel pump would generate around 60 to 80 PSI, but it can be 45 to 55 PSI for some models. It comes down to what the manufacturer recommends for your vehicle. If the fuel pressure is too low, then it will not work.

Here is a video on how to check the fuel pressure

YouTube video

2. Inconsistent engine revs

Sometimes the engine revs go high without you pressing hard on the accelerator. If this is a new occurrence after changing the fuel pump, you would know there is a problem with your new fuel pump.

The engine surge revs because the fuel pump generally exerts inconsistent pressure while pushing fuel into the engine. 

The solution is to have the fuel pump checked and fixed by a professional mechanic.

3. High-pitched whirring or whining sound

A whirring sound can come from the back of the vehicle as you drive. When you hear this sound, it means the fuel pump may be malfunctioning hence the sound.

A good pump has a soft buzz or hum sound, which is inaudible as you drive.

Normally, you would hear a buzz when you turn the key to the ON position on the ignition. This sound means the fuel pump has engaged and is sending fuel to the engine. If the whining sound is persistent, then the fuel pump has a problem and needs checking.

4. Rough idle or engine stalling

Having a problem with your fuel pump can generally starve your engine from getting enough fuel. When this happens, you may experience rough idling, and sometimes the engine stalls. It becomes harder to keep up with the other vehicles on the road.

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Start by checking the electrical connections of the fuel pump. Are they done correctly? Also, check if you have enough fuel recommended to drive the car. Sometimes it can be as simple as refuelling the vehicle.

Otherwise, have the fuel pump checked in case the problem persists.

5. The fuel pump is new but not working

Just because the fuel pump is new, it does not mean you overlook that it may not be working. We find that it is possible for you to experience such because of improper installation. One common mistake is incorrectly installing the wires supplying power to the fuel pump.

So, check whether the fuel pump was installed correctly. If not, make sure the wiring is done right. If the fuel pump is shortcircuited, you may have to get another one.

Here is how to replace a fuel pump in your car

YouTube video

6. Incorrect fuel gauge readings

You may notice you have fueled the vehicle, but the fuel gauge is not moving. Remember, the fuel gauge relies on the fuel pump’s information to change the fuel indicator’s position. If the readings seem incorrect even after fueling, there could be a problem.

If the problem persists, then the fuel gauge sending unit has a problem. It should be diagnosed and repaired for you to get the correct readings.

Also, try not always to drive the vehicle on low fuel. This is because it is the fuel that cools the fuel pump. If the fuel is too low, it may lead to overheating of the fuel pump.

Sometimes you may also face a fuel gauge that does not work at all. This means that you have a defective fuel gauge sending unit. So, make sure to install a new and quality sending unit that works with the vehicle.

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Troubleshooting a New Fuel Pump

In case a new fuel pump starts to show the problems mentioned above, there are a few tests you can do to understand what could be the issue. These tests include;

  • Fuel pump pressure test

When you have a clogged fuel filter, it can be the reason for low fuel pressure. Start by removing the filter and check if it is clogged. In case of a clogged filter, it is best to replace it with a new fuel filter.

Attach a fuel pressure gauge to the vehicle’s test point and get someone to sit in the vehicle and rev the engine. This should allow you to get the fuel pressure reading. Compare the reading with what the manufacturer recommends in the vehicle repair manual.

If the fuel pressure is too low, the fuel pump will not work great for the vehicle.

  • An electrical test on a fuel pump

The first thing you would check in regard to this test would be the fuel pump fuse. This varies from one vehicle to another. It could be in the engine bay or under the steering.

If you establish that the fuel pump fuse has a problem, replace it and turn on the vehicle again.

You can also check the wiring connection on the fuel pump itself. Is the wiring done correctly? This should be enough reason the new fuel pump is not working. Ensure the wiring is correct, and the fuel pump should start working.

Can the wrong fuel damage the fuel pump?

Wrong fuel can damage the fuel pump. A good example is that you now have gasoline in a diesel engine. When this happens, gasoline fuel is not a good lubricant for a diesel engine. The result is too much friction between the various components that may lead to engine damage, plus the fuel pump.

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When you put diesel in a gasoline vehicle, the effects are less serious and can lead to more trouble. The diesel fuel will coat the spark plugs; thus, an engine has trouble firing. The result is misfires, and the engine can fail to start. It is advisable to drain the fuel system to prevent further damage.

How to Avoid Trouble After Changing Fuel Pump

So you have just bought a new fuel pump and would like to replace the old one. Well, you can avoid having trouble after changing the fuel pump if you consider the following;

  • Ensure the fuel pump you install is meant for the vehicle model and make.
  • The installation should be done by a professional. This means there should be no mismatch in the fuel pump’s wiring.
  • It is best to check the fuel pump and its housing rather than small parts of the fuel. This can guarantee that the new fuel pump will work.
  • Keep the fuel tank above 25% most of the time. This should help avoid overheating and failing the fuel pump.
  • Make sure to use the right fuel tank gasket size. The gasket ensures the fuel pump is correctly secured to avoid having air in the tank.
  • Do not allow debris to get into the fuel tank while changing the old fuel pump for the new one. The last thing you need is to change the fuel pump again because of clogging.


Can a new fuel pump go bad?

The wrong installation is the biggest reason a new fuel pump would go bad. If you install it incorrectly, you may end up shortcircuiting the fuel pump. Also, overheating and contamination can damage a new fuel pump.

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Do you have to disconnect the battery to change the fuel pump?

You must disconnect the battery negative terminal while changing the fuel pump. This is vital in ensuring you do not have accidental sparks from the battery while reconnecting the fuel pump.

What does it sound like when you need a new fuel pump?

You would know the fuel pump is damaged when it produces a loud and continuous whining or whirling sound. You would not normally hear the fuel pump sound while driving, so it is reason enough to know you need a new fuel pump when it is persistent.

What is the average life of a fuel pump?

Most of the time, fuel pumps would last over 100,000 miles. That is when you may notice the signs of a worn fuel pump. 100K miles for most drivers is 8 to 10 years of driving the vehicle. This is not bad as it would have served you for a long time.

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