Common Problems After Changing a Fuel Pump

You just changed your fuel pump, and unfortunately, you started experiencing issues with your car. It can be disappointing since you expect it to serve you long enough after getting a new fuel pump.

However, don’t worry yourself much, it is a common problem and happens to other car owners.

Some common problems after changing a fuel pump include; a failure of the fuel pump to work after replacement, hard start, fault in the fuel gauge readings, and rough idling engine.

The issues might have been caused by an incompatible after-market pump, poor installation, or a fault in the fuel sending unit.

This article explains the common problems after changing fuel pumps and how to fix them.

Common Problems After Changing a Fuel Pump

1. Engine Start Difficulty

After changing the fuel pump, it might be challenging to start your vehicle’s engine, or your vehicle might crank for a few seconds before it starts.

It is due to the new pump lacking adequate pressure to move fuel to the engine .

Lack of enough pressure or if no pressure at all, your engine may even stop while driving.


You should remove the line connecting the fuel filter and install a fuel pressure gauge. Plug a hose in the line connecting to the filter.

The average fuel pressure in many vehicles is between 60 and 80 PSI. However, to some car models, it is 45 to 55 PSI.

Check your car’s manual for the right fuel pressure ranges to find an accurate reading.

2. Engine Runs Roughly after A Fuel Pump Change.

After changing the fuel pump, some vehicle engines run or idle roughly.

Rough idling means that you can’t speed up or you cannot keep up with other vehicles. You also take longer to stop or have a problem accelerating uphill. The issue might be due to a lack of fuel for a longer time. However, some people might disagree with the assumption because the engine might run roughly after installing a new fuel pump.

So what is the exact cause?

If your vehicle idles or runs roughly after changing the fuel pump, you could have installed the fuel pump improperly. Specifically, the wiring harness could be the problem. At the same time, the fuel pump might not be receiving power via your system.


To fix this issue, do a thorough check of all your connections in the electrical system. Ensure they are secure and in good contact with the engine and their counterparts.

3. Inconsistent Fuel Gauge Readings

You might experience inconsistent fuel gauge readings after installing a new fuel pump. Sometimes it may read full or empty randomly and is caused by bad wiring.

When changing a fuel pump, you can decide to change the pump and motors only or the entire fuel pump casing, which has the fuel gauge sending unit.

The sending unit helps to read the gas level in the fuel tank.

If you change the motors and the pump only, the fuel gauge might end up breaking because of too much pressure from high temperatures and fuel.

Therefore, if you often drive with your fuel tank less than 25% full, it will lead to high temperatures, damaging the fuel pump and causing the malfunctioning of the fuel gauge.


Change the complete fuel pump casing and ensure you do the wiring correctly. Also, make sure you fill your fuel tank above 25% of the full capacity.

4. Sudden Engine Revs

Imagine driving at a particular speed, and your car starts to accelerate suddenly! Or your engine starts to rev up even without you pressing the accelerator pedal harder!

Well, that can give you a huge scare, and it can be dangerous at the same time.

This engine surge happens if your fuel pump puts inconsistent pressure when changing fuel into the engine.


Call in a professional mechanic to check and fix your fuel pump immediately.

5. Fuel Gauge Not Working

If you change a fuel pump and your fuel gauge stops working or starts to malfunction, your fuel gauge sending unit is defective or is poor quality.


Install a good fuel gauge sending unit that is proper based on your car maker’s specification.

6. Loud Whirring

If you hear a loud whirring at the back of your fuel tank, it indicates that your fuel pump is malfunctioning.

A good fuel pump should produce a soft buzz which is mostly inaudible when driving.

To confirm if the sound is not a cause of alarm, turn on the ignition with the fuel cap open to check if your car is in good condition .

If you hear a buzzing sound, your car is good. If you don’t hear any sound, it means your fuel pump is malfunctioning or not working.


Take your car to the mechanic for further checking and fuel pump replacement.

7. Fuel Pump Not Working

Most of the time the fuel pump’s issue failing to work after a replacement is overlooked.

For instance, the fuel pump may fail to work because of improper installation. You might have been it installed upside down or the wire harness not matched properly. It means that the face and the pump relay may work well, and the circuit might not be functioning.


If you have replaced the fuel pump and it does not work, check all wires in the way of the fuel pump and ensure they are connected correctly.

How to Prevent Common Problems after Changing a Fuel Pump

Here are the tips to help you prevent common problems after changing the fuel pump

  1. Ensure that your car is in a safe space for working on it before changing the fuel pump.
  2. Before installing the new fuel pump, make sure all connections are in good contact with their counterparts.
  3. When changing the fuel pump, make sure you invest in quality parts. Parts of low quality will affect the readings on your fuel gauge after starting the car.
  4. Invest in quality fuel gauge sending units. It will make your car avoid hard starting and running roughly if the tank is empty or has been sitting for a short time.
  5. Ensure no loose connections after installing the fuel pump and use a cool engine to test it.
  6. After changing the fuel pump, test your vehicle in your driveway or private environment. So not try it on a public road with traffic.

Final Thoughts on Common Problems after Changing Fuel Pump

This article shows that incompatible parts and improper installation cause common problems after changing the fuel pump.

However, if the problem happens due to a fault in the new part you had bought, ensure you have the receipts for replacement.

It is crucial to understand the art of installing the fuel pump correctly.

If you feel it’s challenging installing them yourself, seek help from a professional repairer or a mechanic.

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