Common Problems After Changing Fuel Pump and Fixes

Are you facing some drivability issues after changing your car’s fuel pump? Is the car stalling or hesitating to start? It is important to note that changing a fuel pump may reveal some challenges after the replacement.

Since the fuel pump is very vital in the fuel circulation of every car, it is vital to keep the component in good condition or properly fix it in case of a replacement. Otherwise, a vehicle may face several problems, especially the inability to start the engine.

However, the common problems after changing the fuel pump are not without solutions. Let’s find out the common issues and how to fix each of them. If you just installed a new fuel pump and you are wondering what would cause a new fuel pump to go bad, this information could be helpful.

Common Problems after Changing a Fuel Pump

just replaced fuel pump car wont start

There are a couple of issues common to fuel pump replacement. They usually surface after changing a car’s fuel pump.

If you are asking, “Can a fuel pump fail suddenly after installation?” A fuel pump failure may not be the issue after a new installation. The following are some of the problems and how to fix each of them.

Problems: Engine start difficulty

One of the most common issues after changing a fuel pump is hard starting; this is usually due to a lack of fuel pressure.

So, if the car sits for a while, it may have to crank for a few seconds before starting. However, in some cases, someone may experience a situation of no fuel pressure but the pump works.


Since the major cause of a hard start after the fuel pump change is the lack of fuel pressure, the solution to this problem would be to remove the fuel line that connects to the fuel filter. Then, get a fuel pressure gauge installation.

Thereafter, plug a hose and get it connected to the line that links to the fuel filter. Then, open the vehicle’s vents on the hood to enhance ventilation.

After this, the fuel pressure would be set around 45 PSI to 80 PSI, depending on the car. However, it is essential to refer to the vehicle’s manufacturer’s manual to determine the correct fuel pressure.

If the problem remains, you may have to consult an expert auto mechanic to fix the issue as soon as possible.

Read: Common Problems After Head Gasket Replacement and Fixes

Problems: Inconsistent fuel gauge reading

Another common problem is an inconsistent fuel gauge reading. Sometimes, after installing a fuel pump, the fuel gauge may start malfunctioning by displaying “full” or “empty” at random intervals. The main cause of this problem is a defective fuel gauge unit.


If you discover that your car’s fuel gauge reads inconsistently (full or empty) at random, the solution would be to replace the sending units completely.

If you installed a complete fuel pump housing that includes the sending unit, you might have to get a better-quality sending unit. This is because the sending unit may have broken down due to pressure from fuel or high temperature.

If you are also asking, “Can a fuel pump turn on and still be bad?” The analogy of the fuel gauge inconsistency is a typical example. The fuel pump may turn on and not work due to a wiring issue.

Problems: Fuel gauge not working

A completely stopped fuel gauge is another challenge a car owner may face after changing a fuel pump. In this case, the fuel gauge doesn’t read at all.


This issue is also caused by a defective or low-quality fuel gauge sending unit. The way out is to get a new replacement for the fuel gauge sending unit with a more quality one. Also, note that breaking in a new fuel pump may not be necessary; simply plug and play.

Problems: Engine stalling or running rough

Engine rough idling/running and engine stalling are also common with fuel pump replacement. After installing a fuel pump, a car may still run or idle roughly. In some cases, the vehicle may stall consistently until the engine can no longer start after a few minutes.


Engine stalling and rough idling/running are usually caused by the fuel pump’s inability to supply sufficient fuel to power the engine. This is due to the wrong installation of the fuel pump. There may also be a fault with the fuel pump’s wiring harness.

The solution is to inspect all the electrical system connections in the car, especially those linked to the fuel pump. If there is any faulty connection, kindly fix them.

If the connections are okay, you may have to remove the fuel pump and install it correctly. If you can’t do this as a DIYer, kindly contact a professional auto mechanic.

common problems after changing fuel filter

Read Also: Common Problems After Engine Replacement

Tips for Preventing Common Problems after Changing Fuel Pump

Understanding these simple tips will help you avoid the common problems associated with the “post-installation” of a fuel pump in a car.

  • Ensure that the fuel pump is not installed upside down but correctly installed.
  • Install a new fuel filter simultaneously after changing the fuel pump. However, you may also need to find out some common problems after changing the fuel filter to avoid them.
  • Instead of changing only the fuel pump, install complete fuel pump housing.
  • Clean debris and rust from the fuel tank (especially the top).
  • Clean the interior of the fuel tank with minimal suds detergent and water, then dry the fuel tank appropriately.
  • Avoid always running on an empty fuel tank, as it can damage the fuel pump.


What else should you change when changing a fuel pump?

Whenever a car’s fuel pump is changed, it is also necessary to change the fuel filter because it is responsible for trapping dirt and other contaminants from gaining access to the fuel pump.

Dirt and other contaminants can easily result in fuel pump failure, so the best thing would be to install a new fuel filter because the old one may be bad or faulty.

Also, changing a car’s fuel pump may warrant checking the fuel line that runs from the car’s tank to its pump. In that case, it would necessarily require the installation of a new hose.

How long does it take for a new fuel pump to work?

A typical fuel pump installation shouldn’t take more than 1 hour in a car. However, replacing a car’s complete fuel assembly and dropping the fuel tank will take between 2 and 3 hours.

So, a fuel pump is not expected to take the whole day before working. You may also need to find out how to start a car after replacing a fuel pump to avoid complications. However, kindly consult a professional mechanic if you ever need to change a car’s fuel pump

What happens if you put a fuel pump in the wrong?

Wrongly installing a fuel pump will make the fuel pump not supply sufficient fuel to the car’s engine. Also, it may not work at all if installed wrongly. This can be very frustrating because you will have to adjust or remove and reinstall the fuel pump to ensure it works well.

So, it is essential to know exactly how a fuel pump should be installed to avoid the unnecessary stress of adjusting or reinstalling because of a wrong initial installation. If you can’t do it yourself, kindly consult an expert auto mechanic for the job.

Why is my new fuel pump not working?

If a fuel pump does not work well or work at all, it may be due to a wrong installation. Besides wrongly installing a fuel pump, if the component fails to work, it may also be due to a fuel pump circuit problem or a bad fuel pump.

However, if you are sure that everything mentioned above is in good condition, then you may have a defective fuel pump relay, or you may have a faulty ignition switch.

In any case, kindly consult an expert auto mechanic to check what could be wrong with the fuel pump or any of its components.

Final Words

A faulty fuel pump can be a serious challenge, but it is more frustrating to install a new fuel pump and still experience some of the common problems after changing the fuel pump, as outlined above in this article.

So, it would be best to pay close attention to every detail of this article, especially in ensuring that you are able to avoid experiencing these problems from the onset. However, if these problems surface, kindly contact a professional auto mechanic if you can’t handle them.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

2 thoughts on “Common Problems After Changing Fuel Pump and Fixes

  1. Hey Pete,

    I would recommend you to unplug the wiring harness and inspect the pins. It’s likely there is a breach some where. In most cases, it could be the connector 4 and 5 are touching. The connector 4 and 5 are what supply power to the pump.

    Another thing is, did get one of these cheap pumps? It could be the cause. However, the chances is very small.

    If none of these could solve the problem, I’d recommend you drive to a nearby auto shop and have the technicians take a closer look.

  2. I have a 2010 charger. I changed fuel pump and it’ll start and run great . But then it won’t start. I unplug fuel pump and plug it rite back in and it starts great again. It might run great for a day or weeks and then act up again and all it takes is unplug pump and plug rite back in and it’s fine again . It gets irritating

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