Changing a fuel pump can either make or break your car’s overall performance. If done right it can improve fuel consumption and improve engine performance. On the other hand, if done incorrectly, it can lead to a myriad of problems.
The problems can then lead to the weakening of the fuel pump. If the engine start malfunctioning and overheating, it will cause the fuel pump to overheat and then end up damaging the fuel pump.
Keep reading to learn any issues that may be cause by wiring the fuel pump wrong.
What happens if a fuel pump is installed wrong?
If a fuel pump isn’t installed correctly, it either won’t work at all or won’t supply enough fuel to the engine. When the fuel pump isn’t working right, your engine isn’t getting the amount of fuel it needs to run well. Your engine loses power and fuel efficiency.
Below are some potential problems after replacing fuel pump that may result from faulty pump installation;
Quick deterioration of the new fuel pump
Reusing an old connector can result in an intermittent or poor connection. An intermittent connection can cause stumbling when the connection is jarred. A poor connection can cause enough resistance to lower the amount of voltage reaching the pump. This causes the pump to turn more slowly than it should, and can shorten the life of the pump.
Replacing the vehicle side connector should solve the issues with poor connections, but sometimes causes another problem. It’s really easy to mis-wire a new connector, when all the wires leading to it are dirty brown. Cleaning the wires, and taking a picture the connector before cutting it off is a good idea.
Potential pump malfunction
A partially clogged fuel filter can kill the pump. A clogged fuel filter makes the pump work harder, shortening its life. Some older cars have a separate fuel filter. You need to always check for a fuel filter in every vehicle you work on. If there’s one, you need to replace it along with the fuel pump.
Increased emission production
When you drop the fuel tank, it’s always a good idea to put a new gasket on it when you install the fuel pump. Avoid using universal sized gaskets. You need to always make sure that you’re using the correct size. If you use the wrong sized gasket – whether it’s too big or too small – air will get into the fuel tank. This can trigger an emission systems code, and dropping the tank to put a new gasket in is an expensive fix.
Clogged fuel pump
It’s common for dirt and debris to build up on the outside of the fuel tank. When you remove a fuel tank, it’s easy for some of that debris to fall into the fuel tank and contaminate the fuel. When you have contaminated fuel, the strainer at the bottom of the fuel pump will clog up faster. This will lead to premature fuel pump failure. The good news is it’s very easy to prevent this. All you need to do is take the time to clean the debris off the fuel tank before dropping it.
Common problems to expect, their causes, and how to fix them
Below are some common problems you may expect if you new fuel pump is not working properly;
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.
Cause
More often than not, if you encounter this issue, it is likely to be an improper installation. It is common to install the fuel pump mismatched. That is with the line that draws fuel from the tank set to be in the engine and vice versa.
Since the fuel pump can’t draw any fuel from the engine, it will not work. This is the most common installation error. But this is not the only possibility. There is a chance that the pump relay and fuse might not be working. This will also result in a fuel pump that is not working.
Solution:
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.
No Fuel Pressure but Pump Works
If there is no fuel pressure, your engine might even quit while running. This is because the new pump lacks the appropriate pressure to send fuel to the engine.
Cause
The causes of no fuel pressure but pump works can be numerous. However, the most common cause is a faulty fuel pump relay. When the relay is faulty, it can cause the fuel pump not to receive power, which will prevent it from working.
Other causes can include a clogged fuel filter, a failed fuel pump, or a faulty fuel pressure regulator. The solution to this problem is to replace the faulty relay with a new one.
Solution:
The solution to this problem is to replace the faulty relay with a new one. Additionally, it is also essential to check the fuel filter and fuel pressure regulator to ensure they are not the cause of the problem. If either of these components is faulty, they will need to be replaced.
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.
Note: To get an accurate reading, refer to your vehicle manual for the proper fuel pressure range.
Engine start difficulty
One of the most common issues after changing a fuel pump is a hard start after replacing the fuel pump. 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.
Cause
If your car is having trouble starting after putting gas in it, there are a few possible causes. One possibility is that the fuel pump is not correctly aligned. Another possibility is that the fuel line is clogged.
Solution:
The solution to this problem will vary depending on the cause. If the fuel pump is not aligned correctly, you will need to fix it. If the fuel line is clogged, you will need to clean it out.
Since the major cause of hard start after 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.
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 your fuel gauge is reading incorrectly after you’ve changed your fuel, it’s likely due to a problem with the sending unit. The sending unit is what tells the fuel gauge how much fuel is in the tank. If it’s not working properly, it can cause the fuel gauge to give a false reading.
Cause
There are a few things that can cause the sending unit to fail. One is a build-up of dirt and debris on the unit. This can happen if you don’t regularly clean your fuel tank. Another possibility is that the unit itself is damaged or faulty.
Solution:
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 of sending unit.
If you think the problem is with the sending unit, the best solution is to take your car to a mechanic and have them check it out. They can clean or replace the unit, depending on what’s wrong with it. If the problem is with the fuel pressure gauge itself, they can also repair or replace that.
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.
The fuel gauge is 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.
Cause
One possibility is that the problem lies with the fuel sender unit. This component sends a signal to the gauge telling it how much fuel is in the tank. If this unit isn’t working correctly, it can cause the gauge to give an inaccurate reading.
Another possibility is that there is a break in the wiring between the fuel sender unit and the gauge. This is often caused by a problem with the connector plugs into the gauge’s back.
Solution:
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.
If you’ve recently had your oil changed and your fuel gauge isn’t working properly, you can check a few things.
- First, make sure that the sensor in the oil tank is connected correctly. If it’s not, the gauge may not get an accurate reading.
- Also, check the wiring to see if there are any loose connections.
- Finally, if the problem persists, you may need to replace the fuel gauge itself.
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 until after a few minutes.
Cause
One of the most common causes of a car stalling after getting gas is a dirty or blocked fuel filter. The fuel filter is responsible for keeping impurities from entering the engine, and over time it can become clogged with dirt and debris. If the fuel filter is not replaced regularly, it can cause the engine to stall.
Another possible reason for a car stalling after getting gas is a problem with the fuel pump. The fuel pump is responsible for delivering fuel to the engine, and if it is not working properly, the engine can stall.
If the fuel pump cannot supply sufficient fuel to power the engine, it will cause 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.
Solution:
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.
If you notice that your car is stalling after getting gas, try cleaning the fuel filter or adjusting the fuel pump. If the problem persists, consider taking your car to a mechanic to have it checked out.
The solution is to inspect all the electrical system connections in the car, especially those linked with the fuel pump. Ensure that all the electrical connections from your fuel pump are secure and correctly connected. Then fix as needed. Lastly, confirm there’s enough fuel in your tank.
Sudden Car Acceleration
Sudden car acceleration is another possible problem that can occur after changing the fuel pump. If you notice that your car often loses power when you try to accelerate from a stop, your fuel pump may be in trouble. Accelerating requires more fuel, forcing your fuel pump to work harder.
If your pump is failing, it may not be able to keep up with this increased demand, starving your engine of fuel as it tries to accelerate. If your car acts like it’s about to stall when you try to accelerate from a stop, you may need to have your pump inspected.
Cause
There are a few different reasons why sudden car acceleration can occur. It could be due to a problem with the vehicle’s accelerator pedal, a problem with its computer system, or a problem with the engine itself.
Solution:
The solution to this problem will vary depending on the cause. If it is due to a problem with the accelerator pedal, the solution may be as simple as replacing the pedal. If it is due to a problem with the vehicle’s computer system, the solution may be to have the system recalibrated.
If it is due to a problem with the engine, the solution may be to have the engine repaired or replaced.
High Pitched Whirring
If you’re hearing a high-pitched whirring sound after changing your fuel pump, consider checking the origin of the problem in the fuel pump.
Cause
The potential cause of the high-pitched whirring sound is that the new pump is not compatible with your car’s fuel system or it is defective. Such pumps can cause all sorts of problems, including decreased fuel efficiency and increased engine noise.
Solution:
If you suspect that your new fuel pump is incompatible or defective, take it back to the store or replace it at your earliest.
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.
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 you do after replacing your fuel pump to make it run better?
Below are some tips to help your new pump perform better;
Use high quality Tier 1 Fuel.
Fuel at brand name petrol stations such as, BP, Sunoco, Shell, Marathon, and Chevron. Additionally, never get fuel if the station is getting fuel at the same time. All of the dirt and deposits are be stirred up and the gasoline pump filters can never catch it all.
Use fuel additives
If you are not burning a tank of fuel every week to 2 weeks make sure that you add an anti-ethanol agent so that the fuel does not jell. This fuel separation is the single most cause of fuel pump and injector failure.
Do not wait till the gas tank is empty
Keeping at least ¼ tank of fuel in your gas tank at all times. When the tank is at least ¼ full there should be liquid (gasoline) completely surrounding the fuel pump and helping to keep it cool. When the tank is below ¼ tank, part of the fuel pump can be exposed and operate at a higher temperature.
Winterize you gas tank
You can do this by keeping at least ½ tank of gas in the tank at all times. because the lower the fuel level the greater the tendency for water condensation to occur during cold months, creating water in the gas tank. We all know gasoline and water don’t mix, so it is bad to have water in the gas tank and particularly bad when the fuel pump tries to pump water instead of gas into the engine because the tank is low.
Change your fuel filter at 30,000-mile intervals
Having the fuel filter replaced is critical to pump life. When the filter is restricted or plugged it is harder for the pump to push fuel. This increased load on the pump generates more heat which will shorten the pumps life.
Clean your gas tank
Clean your gas tank thoroughly to avoid damaging your replacement fuel pump. A clean fuel tank can also ensure maximum engine performance and fuel efficiency. Follow this 10-step process to clean your gas tank properly and avoid damaging your new fuel pump;
- Drain fuel tank into an approved container.
- Clean rust and debris from the top of the fuel tank.
- Remove fuel pump.
- Swirl gas tank. Pour out remaining gas and debris.
- Clean the tank interior with a low-suds soap and water mixture.
- Swirl cleaning solution inside tank.
- Drain tank and dry with compressed air.
- Wipe out tank with lint-free towel.
- Visually inspect tank. Replace tank if damaged
- Confirm tank is completely dry (may take approximately 30 minutes).
How to start your car after replacing your fuel pump?
After replacing your car fuel pump, it will take between 2-3 hours for it to start working. You have to give the new pump ample time to send fuel with the right pressure to the engine.
If you are replacing a fuel pump for an older car model, (below 2005), then you may have to prime the fuel pump to allow a smooth flow of fuel. Before you start your car after replacing the fuel pump.
On the other hand, if you have a new car model, 2010 and above, you don’t need to prime the new fuel pump after installing it because the fuel pump will draw enough of a vacuum to prime itself.
Follow these steps to prime the fuel tank;
- Fill the fuel tank
- Turn the ignition key to the ON position
- Move the engine Stop/Run switch to the RUN position
- Allow the fuel pump to run until it stops (about 5 seconds)
- Move the engine stop/run switch to the STOP position
- Repeat this process 3-4 times.
Once the fuel is primed, you can go ahead and start you car.
Tips for Preventing Common Problems after Changing Fuel Pump
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 a 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 a 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.