Common Problems After Changing Fuel Pump

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Make no mistake about it; the fuel pump is an important part of your car. Needless to say, without the fuel pump, your car engine won’t get enough fuel needed to function.

And once there’s a lack of fuel supply, the engine stops, and the car is stranded.

By way of analogy, let’s go back to our elementary biology class.

You remember what the teacher said: “once the human heart stops working and can no longer pump air or blood to the different parts, the life in us ceases.’ It’s scary, right?

The fuel pump is the heart of your car engine. It can develop a fault or stop working.

When the latter happens, the best thing to do is to replace it. After changing a bad fuel pump and replaces with a new one, you should brace up for potential issues.

The question is, ‘what are the common problems after changing the fuel pump? Let’s walk through it together.

Common Problems After Changing Fuel Pump

Here are the top 5 complications changing the fuel pump may cause to the car. Some of these problems are interrelated.

Rough Idling

One of the visible issues you may face after replacing your car fuel pump is rough idling.

When the engine stalls, the car won’t be able to speed up. Coming to a complete stop after applying the brake might become difficult.

The inability to accelerate when driving downhill or uphill is also part of a rough idling or engine stalling.

When these signs show up, the question to ask is “were these problems existing before the installation of the new fuel pump.”

If no, then you may want to suspect a faulty fuel pump.

Two things are likely here: the new fuel pump may be supplying insufficient fuel that is only enough to make the vehicle stutter.

The other possibility is the lack of power to make the fuel pump work. The solutions include inspecting the electrical connection and increasing the amount of fuel in the tank.

Hard Engine Start

If you also experience difficulty in starting your car engine after installing a new fuel pump, it’s time to check if the fuel pump is healthy.

When you ignite, your car will crank for a few seconds and then start or shut down. A potential culprit is the fuel pump.

It possibly lacks the needed pressure to direct fuel to the engine for power. Lack of fuel may also cause your engine to shut down or not start while running.

The fix to this is to install a fuel pressure gauge. Start by dislodging the fuel line that links up with the fuel filter and inserting a hose in the fuel line.

Incorrect Fuel Gauge Reading

The function of the fuel gauge is to correctly read the amount of fuel pressure that gets to the engine.

Two things can happen to the fuel gauge after you newly install a fuel pump.

It can either stop working or provide an incorrect reading. The gas gauge can also bounce back and forth from ‘empty’ to ‘full.’

Either way, it’s not safe for your vehicle and engine. You need to keep track of the amount of fuel pressure your engine receives.

Besides, the reading has to be accurate. But if the fuel gauge neither reads nor gives an accurate reading, then the fuel sending unit is the number one potential culprit.

Fuel Pump Failure

The failure of the fuel pump can cause a wiring harness due to the wrong installation.

When you set up the fuel pump upside down, a wiring harness will come in the way of the pump and obstruct its proper functioning.

When this happens, the fuel pump is unable to receive enough energy to power. Worse still, the fuel pump can start to leak gas from under the car tank.

Fuel Gauge Failing

The fuel gauge may stop working completely after installing your fuel pump.

This way, there will not be any indication on the dashboard about the fuel level in your car tank. This is dangerous but also easily predictable.

The issue could be a result of a defective sending unit of the fuel gauge. It can also be because the sending unit is of low quality.

What To Do After Replacing Fuel Pump

Changing the fuel pump alone is not enough. There are steps you must take to ensure the replacement part works as efficiently as it should.

Now that you’ve replaced the fuel pump, here are things you must do to avoid damaging your new one.

Take Fuel Pressure Test

The first task to do after setting up your fuel pump is to carry out a fuel pressure test. This is because the fuel filter may have some clogs in its way.

Doing this is pretty simple and easy. Unplug the fuel filter and drain leftover fuel.

After this, pass a rubber-like hose through the filter pressure vessel. Blow it out before replacing the filter.

Take Fuel Pressure Reading

Another post-installation thing to do is to take the fuel pressure reading. Start by connecting a fuel pressure gauge to a testing point on your car and have a friend rev the engine a little.

Take the reading on the gauge. The normal fuel pressure for a vehicle is 60 and 80 psi. You may find some vehicles with lesser pressure, maybe anywhere around 40 to 45 psi.

You can check the owner’s manual for the minimum and max fuel pressure for your car.

Keep Engine Heat At ‘Significant’ Level

Another way to troubleshoot your freshly installed fuel pump is to rev your engine and keep it at a certain heat level.

This way, you can guess whether the fuel pump is faulty or in good condition. Keep your engine at a significant heat level.

Once the engine cools, the fuel pump can easily reset itself and perform as though it’s not defective.

However, if the engine is heated, you can easily find out the health status of the fuel pump.

Apply External Pressure

Vehicles fuel pump generally operates well under normal circumstances.

But when subject to extreme working conditions through the application of external pressure, it tends to indicate how powerful or defective it is.

And I think this is not just about the fuel pump. The human heartbeat also increases when the heart works under strenuous conditions.

When you apply some external pressure, a defective fuel pump will naturally shut down. If the fuel pump is excellent, it will hold out against the pressure.

Carry Out Fuel Pump Electrical Test

Taking the auto fuse through an electrical test is another step you should take after installing your car fuel pump.

The fuse supplies the needed power to the fuel pump and once it’s defective, the pump is denied its power to function.

To carry out the test, pull out the fuse and check if it’s burned or broken. Check other fuses connected to the electrical components.

If there’s a problem with any of the fittings, you’ll need to replace them.

New Fuel Pump Not Working

At times, you may notice that a newly installed fuel pump won’t work in your car. The natural question will be, ‘what can be the problem?’

It’s possible and there are four important areas you should look out for and these can cause a new fuel pump not to work.

Is The Fuel Pump Properly Installed?

This will be my natural counter-reaction. Once I found out that there was an error in setting up the fuel pump in the first place, I may not probe any further.

A wrongly installed fuel pump will either perform poorly or not work. There is a proper procedure to follow when installing a fuel pump.

You can either hire a certified technician or go the DIY way.

In 2 hours, you should be done with a DIY installation of your car fuel pump. Don’t forget, you’ll need a few small hand tools to complete it.

Is The New Fuel Pump Compatible With Your Car?

It sounds weird, right? Not all fuel pumps are designed for all cars. Each car model and make comes with specifications for all its parts.

A fuel pump that will work for Toyota Corolla may not be what Toyota Camry will need. Let me shock you further.

The fuel pump for a 2009 Toyota Camry may not work for the same model made in 2016.

You need to read the owners’ manual to know the right replacement fuel pump for your car.

Is The Wiring Circuit In Order?

The wiring circuit is the automotive fuse-like housing of the entire electrical compartment of the fuel pump. It combines with other electrical fittings of the car engine.

Any break in the circuit connection can cause the fuel pump to be short of power.

If wrong wires are used to connect the entire circuit or the wiring is incorrectly done, the power due to the fuel pump will be cut short.

Is The Fuel Pump Relay Bad?

A faulty fuel pump relay can also cause the replacement fuel pump not to work. The function of the relay is to send an electrical current into the fuel pump.

This will ensure that the fuel pump receives needed electrical energy to power and function effectively.

Once the fuel pump relay is faulty, it breaks the electrical contact with the fuel pump and the pump won’t work.

Fuel Pump Getting Power But Not Working

There is a possibility that the fuel pump replacement is receiving power but yet not working. A few things are likely responsible.

The fuel pump may not be the right pump designed for your vehicle. There may also be an issue with the wiring or electrical connection.

Ultimately, the sending unit receives the greatest flak. Even if the fuse sends needed power, a failing sending unit won’t make the fuel pump work.

And until you replace the unit, the fuel pump will fail your car engine.

Tips To Do To Prevent Fuel Pump Failure

There are things you can do to ensure that your fuel pump at all times perform optimally and is not damaged before its time.

Although the fuel pump is covered under the manufacturers’ warranty, you can save yourself a lot of stress.

Here are things to do to prevent fuel pump failure:

Clean Your Gas Tank

Here are steps to clean your car fuel tank:

  1. You should empty the fuel tank of all fuel and fuel residue.
  2. Remove the stains, carbon despot, rust, and debris on top of the fuel tank.
  3. Take out the fuel pump.
  4. Vigorously spin the gas tank to completely empty any leftover gas and liquid.
  5. Thoroughly clean out the inside of the fuel tank using soapy water.
  6. Flush out the low-suds soapy water.
  7. Evacuate the fuel tank and dry with compressed air.
  8. Use a lint-free towel to clean the fuel tank.
  9. Check if there’s any damage to the interior and exterior part of the fuel tank.
  10. Allow the tank to dry completely for about 25 minutes before reinstalling.

Avoid Driving On An Empty Tank

One disservice you can do to your fuel pump and the engine is to run on an almost empty gas tank.

As a matter of fact, when the gas is getting below one-quarter of the total engine capacity, it’s time to refuel.

Install Fuel Pump Properly

Wrong fuel pump installation can cause a catastrophe, trust me.

So, what you want to do is to ensure that the fuel pump is set up properly and not upside down.

An accurate installation will make the fuel pump receive power as it should.

Use High-Quality Fittings

When changing the fuel pump, it’s best to use high-quality replacement parts. An OEM fuel gauge, fuse, fuel pump, or other parts will do a better job than aftermarkets.

Even if you’re going for aftermarkets, ensure they’re the top grades. Use the right parts compatible with your car model and make.

Don’t also forget to change the entire fuel pump housing when replacing your fuel pump.


From my interaction with you so far, you can see that the fuel pump plays a central role in the overall functioning of the engine and the life of your car.

Once you change the fuel pump component, some issues may arise. These common problems after changing the fuel pump are not out of this world.

They are issues you can handle using a DIY procedure. What you should do is to pay attention to the signs early enough and tackle them head-on and without delay.

The next time you replace a failing fuel pump, you should expect certain issues to raise their ugly heads. Guess what?

You can prevent some of the problems. Again, it goes back to knowing what these potential glitches are and what to look out for.

I hope this article helps you understand these complications and how you can prepare ahead before they deal your car a heavy blow.