After changing your fuel pump, your car should run smoothly without any hitches. However, sometimes you may find that your new pump does function as expected. You may find that your car makes noise when accelerating at a low speed.
The most common problems after changing a fuel pump are:
- engine start difficulty
- inconsistent fuel gauge readings
- fuel gauge not working
- engine stalling
- rough idling
- loud whirring noise
It may be that the pump was not installed correctly or is incompatible with your car. Whatever the reason, it can be very frustrating. But before you have a meltdown, you might want to read this to learn some common problems that occur after changing the fuel pump:
1. Engine Start Difficulty
You may have trouble starting your car engine, or the car cranks for a few seconds before starting.
The main cause is that the new pump lacks the appropriate pressure to send fuel to the engine. Sometimes, if there is no fuel pressure, your engine might even quit while running.
Remove the fuel line that connects to the fuel filter, and install a fuel pressure gauge. Then plug a hose in the line going to the filter.
The standard fuel pressure in most cars should be between 60 and 80 PSI, although it’s 45 to 55 PSI for some models.
To get an accurate reading, refer to your vehicle manual for the proper fuel pressure range.
2. Inconsistent Fuel Gauge Readings
After installing a fuel pump, your fuel gauge may start to display either empty or full randomly. A common cause for this is bad wiring.
Changing a fuel pump can entail changing the pump and motors only or the whole fuel pump casing that consists of the fuel gauge sending unit.
The fuel gauge sending unit is the one that reads the gas level in the fuel tank.
In rare cases, if you only change the pump and motors, the fuel gauge can break due to high pressure from fuel or high temperatures. If you frequently drive with your fuel tank less than 25% full, it causes high temperatures. This, in turn, damages the fuel pump and causes the fuel gauge to malfunction.
Change the whole fuel pump housing and check that the wiring is done correctly. Additionally, ensure your fuel tank is filled with more than 25% of the full capacity.
3. Fuel Gauge Not Working
When you install a new fuel pump, your fuel gauge may malfunction or altogether stop working. This issue is caused by a defective or low-quality fuel gauge sending unit.
You will need to install a new quality fuel gauge sending unit that’s according to your car manufacturer’s specifications.
4. Engine Stalling and Rough Idling
If your engine is stalling or rough idling, you cannot speed up or have trouble keeping up with other vehicles. Sometimes it can take a while longer to come to a complete stop as your engine keeps stalling out. Or you might struggle to accelerate when going uphill or downhill.
In this case, ask yourself whether the car’s engine was running smoothly before. If it was, then the problem lies with the new fuel pump.
Likely, the fuel pump cannot supply sufficient fuel to power the engine, causing the car to sputter when you try to accelerate and maintain a certain speed. Or it may be that the fuel pump is not getting enough power to supply fuel through your system, often due to a bad connection of the pump’s wiring harness.
Check that all the electrical connections from your fuel pump are secure and correctly connected. Also, confirm there’s enough fuel in your tank.
5. Fuel Pump Not Working
There might still be problems after replacing your fuel pump does not necessarily mean it will work. This is a common problem often overlooked.
There are a couple of causes for this problem, the most common being improper installation. In most cases, you’ll find it was installed upside down with the wire harness mismatched. The pump relay and fuse might be working okay with only the circuit not functioning.
Here’s what to do after replacing the fuel pump, check for any wires in the way of your fuel pump and wires that are not correctly connected.
6. Sudden Engine Revs
When maintaining a certain speed and your car suddenly accelerates, or your engine revs up without you pressing harder on the accelerator pedal, it can be a huge scare. It’s also dangerous.
This sudden engine surge occurs when your fuel pump exerts inconsistent pressure when injecting fuel into the engine.
Take your vehicle to your mechanic immediately to get your fuel pump checked and fixed.
7. Loud Whirring
When you hear high-pitched whining or whirring at the back of your car where your fuel tank is located, it spells a malfunctioning fuel pump.
A good fuel pump emits a soft hum or buzz that is usually inaudible while you drive.
You can confirm if it’s in good condition by turning the ignition on while the fuel door and cap are open. You should hear a buzz. If you don’t hear any sound, then your fuel pump is not working.
How to Troubleshoot Fuel Pump Problems
It’s possible that your fuel pump is broken or clogged, which can be caused by a variety of factors, including faulty wiring, wear and tear, and so on. It is critical that you know how to troubleshoot the system in order to identify the exact problem.
Fuel Pump Electrical Test
A fuel pump’s power supply, which is usually a fuse, must be tested for an electrical test. The location of the fuel pump fuse varies depending on vehicle types, models, and other factors.
So you’ll need to look in your car’s owner’s handbook to find out where yours is. When you’ve found it, pull it out and check if it’s broken (or burned). If the fuse seems undamaged, look at other fuses that are linked to the fuel pump system.
After checking the fuses and finding that they were all OK, have a friend start the vehicle (turn it on) while you listen for the fuel pump relay to click. If this sounds complicated, have a mechanic do it for you.
Fuel Pump Pressure Test
Acceleration difficulties can be caused by a clogged fuel filter. Remove the filter and drain the remaining fuel first. After that, connect a short rubber hose to the filter inlet and blow it out; then replace the filter.
Get a fuel pressure gauge, attach it to your car’s test point, and have someone else rev your engine while you check the reading on the pressure gauge. The pressure gauge should read somewhere around what is stated in your vehicle’s repair manual.
What should I do after a fuel pump replacement?
Follow these 10 easy steps to properly clean your gas tank and avoid damaging your new fuel pump:
- Drain the fuel tank into a safe container
- Clean out any debris or rust from the top of the fuel tank
- Remove the fuel pump
- Swirl any remaining liquid in the gas tank then pour any leftover gas and debris
- Clean the interior of the fuel tank with a low-suds soap and water mixture
- Swirl the cleaning solution inside the fuel tank
- Drain the fuel tank and dry it with compressed air
- Wipe down the fuel tank with a lint-free towel
- Visually inspect the fuel tank for any damages
- Wait approximately 30 minutes for the tank to completely dry
Tips for Avoiding Problems After Changing Your Fuel Pump
Below are some tips to help you avoid running into problems associated with changing your fuel pump.
- Ensure the fuel pump installed is the right model for your vehicle.
- Ensure the fuel pump is properly installed and there’s no mismatch on the relay and wiring harness.
- Change the complete fuel pump housing instead of just the fuel pump.
- Avoid running on an empty fuel tank or below 25% of the total fuel capacity.
- Do appropriate tests to ensure everything is in order before driving.
Here are some frequently asked questions regarding common problems people face after changing their fuel pump:
Why Does My Car Make Noise When Accelerating at a Low Speed?
Your car makes noise when accelerating because the engine is over-exerting itself. This can be due to not receiving enough fuel from the fuel pump or insufficient fuel pressure.
Can I Drive With a Bad Fuel Pump?
No, you cannot drive with a bad fuel pump. Even though the fuel may still make it to the engine, you might cause other problems if you drive with a bad fuel pump.
In most cases, your car engine will not start.
Are There Other Parts I Can Change Together With My Fuel Pump?
Yes. Changing your fuel pump can warrant a change of your fuel filter. The filter is responsible for trapping dirt and other impurities from the fuel.
When dirt passes through the filter, it can damage your fuel pump. Therefore, the best thing would be to install a new fuel filter alongside your fuel pump.
Why Is My Replaced Fuel Pump Not Working?
There are several reasons a fuel pump will not work after replacing.
The most common reasons are the fuel pump was not installed correctly, or the wiring circuit and fuel pump relay has a problem.
The most common problems that occur after changing your fuel pump–engine stalls, rough starts, loud whining, and inconsistent fuel gauge readings, occur when there is a bad installation of the fuel pump or some parts that don’t match.
To avoid these problems, ensure your vehicle is in a safe area to work on before changing your fuel pump. And check that all connections are making good contact. Additionally, test out your car after changing the fuel pump to ensure it’s running smoothly.