Replacing a fuel pump can be tricky, leading to common problems, like frequent engine stalling and a malfunctioning fuel gauge. Even so, every common fuel pump problem has a solution—you just need to know what to do when you encounter it.

The fuel pump is a vital component of your car. It’s responsible for sending gasoline through the engine, causing combustion. Without a functioning fuel pump, your car won’t run. Unfortunately, replacing a faulty fuel pump can cause as many problems as it solves.

If you’ve recently replaced your fuel pump and you’re still having issues, you’re probably wondering what to do next.

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Four common problems after changing a fuel pump

Although changing your fuel pump seems like it should solve your car’s issues, owners often find it creates problems. There are four common problems car owners face after replacing their fuel pump, including:

Difficulty starting the engine

Engine running or idling roughly

Fuel gauge isn’t working properly

Odd noises

If you’ve recently replaced your fuel pump and you’re still having problems, keep reading to learn how to fix it and what you should do after changing your fuel pump.

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1. Engine has trouble starting

The most common problem car owners have after changing their fuel pump is that their engine won’t start or has trouble starting. Sometimes, the engine will even die while you’re driving.

Cause

If your engine is not starting or is struggling to start, the new fuel pump isn’t providing enough fuel pressure. Most cars need between 60 and 80 PSI of pressure to run properly.

If you’re not getting enough fuel pressure, it typically either means that the new pump isn’t powerful enough or that one of the lines wasn’t secured properly, causing a leak.

Solution

First, double-check that all the fuel lines are secure and intact and that there aren’t any leaks. A leak large enough to cause inadequate fuel pressure should be pretty obvious—you’ll notice gasoline leaking from somewhere along your fuel lines.

If there aren’t any leaks, then the pump probably isn’t powerful enough for your car. To test this, you’ll need a fuel pressure gauge.

Disconnect the fuel line from the fuel filter, install the pressure gauge, and then connect a hose to the line attached to the filter. Then, you can get an accurate reading of just how much fuel pressure you have.

Double-check your owner's manual to make sure you know what the appropriate fuel pressure range is for your car. If the reading is outside the correct pressure range, you may need a different fuel pump. If the range is correct, you may have a separate issue that a mechanic will need to diagnose.

2. Engine running or idling roughly

Usually, when your engine is running or idling roughly, it’s because it isn’t getting enough fuel or the fuel pressure is too low.

Cause

If your engine isn’t getting enough fuel, it could be that the pump wasn’t installed correctly, causing poor fuel pressure.

There also may be an issue with your wiring harness. If there’s a short or a fault in the wiring, your pump may not be getting enough power to function correctly.

Solution

Check and recheck all the electrical connections, ensuring they’re securely fastened. If you have a multimeter, use it to test the voltage in the wires. It’s more than likely you’ll discover that the pump isn’t getting adequate electricity. Securing the wiring should resolve the issue.

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Jumpstarting your dead car battery back to life

3. Fuel gauge isn’t working or giving inconsistent readings

After replacing a fuel pump, car owners often encounter issues with their fuel gauge either not working or giving inconsistent and inaccurate readings. There are a couple of possible reasons why this might be happening.

Cause

If your fuel gauge is acting erratic or not functioning at all, the most common cause is that you have a problem with your fuel gauge sending unit. The fuel gauge sending unit is responsible for reading the gas level in your tank.

A less common cause of sending unit trouble is that the unit has become damaged due to excessively high temperatures or fuel pressure that’s too high.

High temperatures are often caused by frequently driving with a fuel tank that’s below 25%—which is a fairly easy fix. If the sending unit was damaged by high pressure, you’ve got a more serious situation on your hands.

Solution

If the fuel gauge sending unit is defective or damaged due to excessive heat, then you’ll just need to replace the sending unit. Make sure to get one that is high enough quality and keep your tank above 25% to avoid the issue reoccurring.

If, on the other hand, the sending unit was damaged from high pressure, you’ll need to replace the sending unit and the fuel pump again. This time, double-check that you get a pump with the appropriate power level.

4. Unexplained noises

Sometimes, car owners notice a loud whirring noise coming from their fuel tank after replacing a fuel pump. If the fuel pump is operating correctly, there should be a faint buzzing noise, but you normally can’t hear it when the car is running. If you can hear any noise coming from the back of your car where the fuel tank is, you probably have a fuel pump problem.

Cause

This happens when the new fuel pump is either defective or improperly installed.

Solution

Check all the connections (fuel lines and wiring). If you have a fuel pressure gauge, test the pressure—it’ll almost certainly be low.

You can also try removing and reinstalling the pump, following the installation procedure carefully. If the issue persists, you likely have a defective part.

MORE:

How far can you drive on an empty tank of gas?

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FAQs

I replaced the fuel pump—why is it still not working?

There are several reasons why your fuel pump may not be working after replacing it. The most likely reason is that it was not installed properly. Double-check that it is securely hooked up to all fuel lines and electrical wires. One common mistake people make is installing the pump upside down.

Can I replace a fuel pump myself?

It depends. Replacing a fuel pump isn’t too complicated—but there are quite a few common mistakes that you could make. Unless you have a good amount of mechanical expertise and knowledge of electrical work, it’s probably best to have a professional do it for you.

What do I do after replacing my fuel pump?

First, test that the pump is working, your fuel gauge is operating properly, and there aren’t any new noises coming from the back of your car. If you notice anything out of place, it may be time for a trip to the mechanic.

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