Common Problems After Changing Fuel Pump: 6 Potential Fixes

So you just replaced your fuel pump and now your car is acting up- don’t worry, you’re not alone. Changing the fuel pump is a crucial component of the car’s fuel system, and if something goes wrong, it can cause your car to stall or even fail to start altogether.

After replacing a fuel pump, it’s essential to be aware of some common problems such as electric issues, fuel leakage, and issues with fuel pressures.

In this post, I’ll draw from my experience and provide some straightforward tips to help you avoid or fix issues after changing fuel pump. So, let’s dive in and get your ride back on the road.

If you want to get a quick answer, you can chat with a virtual mechanic for free.

If you want a video overview of this entire guide on the common problems after fuel pump replacement, I have explained everything in a very concise manner in the following YouTube video:

Common Problems After Changing Fuel Pump

Here are some of the most common problems after changing fuel pump:

• Fuel leaks and fuel pressure problems
• Loose fuel pump
• Electrical issues
• Inconsistent reading on the fuel gauge
• Difficulty starting the engine or engine stalling
• Dust or Debris getting into the gas tank
• Engine Misfires
• Rough Idle
• Poor fuel economy
• Check engine light illuminated on the dashboard
• Accidentally pinching a fuel line
• Loud whining noise from the fuel tank

You can jump straight to the explanation if you have preliminary knowledge of electrical fuel pump. Otherwise, I will suggest to also read the next section before jumping straight to the problems that can occur after fuel pump replacement.

Importance of the Electric Fuel Pump in Car Operation

In the past, fuel pumps were mechanical and driven by the engine’s camshaft. However, modern engines use electrical fuel pumps instead of carburetors. These pumps deliver fuel to the injectors at a defined pressure, and they are switched on by the ECU using electric signals.

When you turn on the ignition, the electric fuel pump runs for a few seconds. Once the engine starts, it runs continuously. The main advantage of electric fuel pumps is their ability to maintain constant fuel pressure, ensuring an easier start for the car.

Another benefit is the prevention of vapor lock, a problem caused by fuel turning into vapor due to excessive heat.

Electric fuel pumps keep the fuel moving through the lines at a constant pressure, avoiding the formation of air pockets that disrupt fuel flow and can cause the engine to stop working.

Unlike mechanical fuel pumps, electric fuel pumps are usually located near the fuel tank at the rear of the vehicle.

This positioning helps keep the fuel cooler, as the pump continuously delivers fuel to the engine at a constant pressure and flow rate. Additionally, being submerged in the fuel tank aids in keeping the fuel pump cool.

A notable advantage is that electric fuel pumps are not physically attached to the engine, allowing for flexibility in size and shape. This flexibility is useful when an exact replacement is not available.

Furthermore, electric fuel pumps are not affected by worn cams on the camshaft, unlike mechanical fuel pumps. Cams are engine components that assist mechanical fuel pumps, but electric fuel pumps operate independently, eliminating this concern.

Lastly, electric fuel pumps can be equipped with a hidden on/off switch as an anti-theft measure. This feature prevents unauthorized individuals from starting the car by disabling the fuel pump.

Overall, electric fuel pumps offer several advantages over mechanical fuel pumps. They maintain constant fuel pressure, prevent vapor lock, and provide flexibility in installation.

What Can Damage Electric Fuel Pump?

Low fuel level in the gas tank can can damage the fuel pump. When the fuel level is low, the fuel pump has to work harder to draw fuel from the tank.

This can cause the pump to overheat, leading to reduced performance and eventual failure. If you have read my article on why a car sputters after getting gas, I have elaborated on how the fuel pump can experience fuel starvation.

In situations where the fuel delivery is insufficient or completely absent, the current consumption increases while the cooling process is effectively halted. As a consequence, gas accumulates within the pump, causing issues in the engine’s fuel supply and eventually leading to pump deterioration.

Another factor that can damage an electric fuel pump is contamination of the fuel system. Dirt, debris, and other contaminants can enter the fuel tank and make their way to the fuel pump, causing damage to the pump’s delicate internal components. 

Electrical issues can also damage an electric fuel pump. Over-voltage or under-voltage conditions can cause the pump’s motor to overheat, leading to premature failure. Additionally, corrosion or damage to the pump’s electrical wiring or connectors can cause intermittent or complete pump failure. 

Problems With Vehicle After Replacing Fuel Pump

Here are the problems your vehicle can face after replacing the fuel pump:

1. Electrical Faults After Installing New Fuel Pump

One common problem after replacing fuel pumps is faulty electrical connections, which is actually the second most frequent cause.

Despite the fact that the fuel pump is fully functional and can deliver pressure and flow well within the standard range, a degraded output is observed as a result of poor electrical connections.

The fuel pump is usually connected to a fuse that protects the electrical circuit. If the fuse blows, the fuel pump won’t work, and you’ll experience similar symptoms to before replacing the fuel pump.

To fix this issue, you’ll have to replace the blown fuse with a new one of the same amperage. You can find the location of the fuel pump fuse in your car’s owner’s manual.

Another possible electrical issue after changing the fuel pump is a faulty fuel pump relay. The relay is a small device that controls the flow of electricity to the fuel pump.

If the relay is faulty, the fuel pump might not receive enough voltage, or it might not work at all. To check if the relay is the problem, you can swap it with a similar relay in your car’s fuse box and see if the fuel pump works. If it does, then the relay was the issue, and you’ll need to replace it. 

When a fuel pump rotates slower due to corroded electric connections, it will not generate suitable fuel pressure, resulting in rough idle or difficulty in starting a car.

When a fuel pump is forced to work harder than it should repeatedly, it can shorten its lifespan, making it weaker, less efficient, and eventually failing completely.

This can result in engine stumbling, as the fuel supply is disrupted leading to the engine temporarily losing power and then regaining it when the connection is restored. Consequently, this can lead to poor overall engine performance and reduced driving safety.

How to fix the problem of bad electrical connection of the fuel pump?

First, you should test if fuses and relays of the fuel pump are damaged or not.

You can read this guide to test the fuses and relays of a fuel pump. The method to test fuses and relays is the same for every electrical component.

Lastly, a short circuit can also occur while changing the fuel pump. This is because, during fuel pump replacement, some mechanics have a habit of disconnecting the negative terminal of the battery.

If, by mistake, they have removed the positive terminal of the battery first, a short circuit could occur. Similarly, the positive terminal of the battery should be connected first. 

Fixing issues for the connector of the fuel pump

You can also use a new connector that comes with a pump assembly if the old connector is damaged.

Now, this is a very tricky process as the color coding of the wires of a new pump connector can be different compared to that of the old one.

If you don’t follow the color coding, it will result in the fuel pump not starting. As a result, your car will also not start after changing the fuel pump.

So, to install the new connector of the new fuel pump over the old connector, cut the wires to the desired length and slice the insulation up to a certain length.

After that, from the reference of the color code diagram of the new connector, match the vehicle wire colors and position to the replacement style connector.

You can watch the below video for a better understanding:

2. Debris Entry in Tank When Changing Fuel Pump

One of the biggest problems that can arise after changing your fuel pump is the introduction of dust or debris into the gas tank. This can happen if the tank isn’t properly cleaned beforehand, or if the fuel lines and filters aren’t replaced along with the fuelpump.

So why is dust or debris in the gas tank such a big deal? There are a few reasons:

1. Clogged Fuel Filters: When particles get into your fuel system, they can clog up your fuel filters. This can cause your engine to run poorly or even stall altogether.
2. Fuel Pump Damage: If debris gets into your fuel pump, it can cause damage to the internal components. This can lead to reduced fuel pressure and flow, which can cause engine performance issues.
3. Fuel Injector Damage: The fuel injectors in your vehicle are responsible for delivering fuel to the engine. If debris gets into these components, they can become clogged or damaged. This can cause rough idling, poor acceleration, and reduced fuel efficiency.

How to fix?

The best solution to prevent dust or debris from entering the gas tank is to be mindful of the type of gasoline you use.

Always use high-quality gasoline that is free of contaminants and has a good reputation. Additionally, avoid filling up the gas tank with old or dirty gasoline that has been sitting in the tank for too long.

During changing the fuel pump, make sure to rinse the entire fuel system with clean quality fuel.

3. Noisy New Fuel Pump Operation Whining Sounds

You can also hear whining sounds from a new fuel pump after installation.

Contaminated fuel and low fuel tank level are the possible causes of a whining noise of a new fuel pump that you have just replaced.

Contaminated fuel can damage your fuel pump and cause it to produce unusual sounds. Dirt, rust, and debris can enter your fuel tank through a clogged fuel filter, and eventually, find their way into the fuel pump.

Another possible cause of a loud whining noise after changing your fuel pump is a low fuel tank level. When your fuel tank level is low, the fuel pump has to work harder to push fuel through the fuel system, which can result in a whining noise. 

The fuel keeps the fuel pump cool as well. If the fuel tank is empty, the fuel pump will wear out faster from excessive heat.

How whining noise from fuel pump can cause problems?

While a whining fuel pump might not seem like a big deal, it can actually lead to some serious problems down the line. Here are a few potential issues to be aware of:

• Reduced fuel efficiency: If the fuel pump isn’t working as efficiently as it should be, your car might start to burn more gas than usual. This can lead to increased fuel costs and a reduced driving range.
• Stalling or failure to start: If the fuel pump fails completely, your car won’t be able to start or will stall while you’re driving.

How to fix the whining noise from fuel pump?

A good fuel pump only emits a soft humming sound which can be only audible if you open the gas cap and bring your ear close to it.

If the new fuel pump is producing a loud whining noise, you should check the filter at the inlet of the fuel pump if it is blocked by dirt and debris. 

Next, you should make sure that the fuel pump must be installed low (“wet”, below the fluid level) in the vicinity of the tank. The fuel level in the fuel tank should not be less than 1/4th of the fuel tank capacity.

4. Clogged Fuel Filter Causing Low Pressure Post Fuel Pump Change

Your fuel filter is responsible for ensuring your car’s fuel system is free of debris and contaminants that can damage your engine.

Over time, the fuel filter can become clogged with dirt, rust, and other particles. This can cause a drop in fuel pressure, which can lead to poor engine performance, reduced fuel efficiency, and engine stalling.

When you change your fuel pump, it’s essential to replace your fuel filter at the same time. This ensures that the new fuel pump is working correctly and that the fuel system is free of contaminants that can clog the filter.

When the fuel filter is quite old and clogged with dirt particles, the fuel pump will have to work harder to push fuel through the fuel filter. As a result, it will shorten the life of a fuel pump.

5. Fuel Leaks and Inadequate Pressure Post Replacement

One common problem that people encounter after changing their fuel pump is fuel leaks. Fuel leaks can be dangerous and costly if not addressed promptly.

Moreover, if the fuel is leaking, it will not have sufficient pressure for an optimum fuel injection through the fuel injectors. As a result, the car will have difficulty in starting and accelerating.

One common cause of fuel leaks after changing a fuel pump is improper installation. This can happen if the fuel pump is not tightened enough or if the fuel lines are not connected properly. 

When installing a new fuel pump, it’s important to tighten the bolts and fasteners to manufacturer specifications. If they are not tightened to the proper torque, these parts could loosen over time and cause a fuel leak.

Here, I would like to highlight that in all vehicles, the fuel pump is secured by a cam locking ring. Now, the way to secure a fuel pump with a cam locking ring is different for each vehicle.

In some vehicles, the fuel pump assembly comes with a metal cover that is tightened with nuts and fasteners. Such vehicles don’t need to have a cam locking ring. Their cover has its gasket attached.

In the figure above, you can see that the fuel pump does not need a cam locking ring. It has a metal cover that is tightened in a criss-cross pattern to secure a fuel pump and avoid fuel leakage.

On the other hand, in some vehicles, a cam locking ring is strategically tightened to secure the new fuel pump.

The tightening method of the cam locking ring can be different for each vehicle. So, make sure to follow the instructions in the owner’s manual.

Furthermore, make sure that you replace the old gasket on the fuel tank with a new one while changing the fuel pump.

How to check for fuel leaks after installing fuel pump?

You need to verify the fuel pressure at the fuel rail to detect any fuel leaks. For this, you need a fuel pressure test kit.

Each vehicle has recommended fuel pressure range. So, you should check your vehicle’s manual. You also have to verify that fuel is reaching the fuel rail. To learn more, you can read my guide on the symptoms of a bad fuel pressure regulator.

How to fix fuel leaks after fuel pump replacement?

If the fuel lines are not tightened enough, they can cause fuel to leak out. Make sure to tighten the fuel lines properly when installing a new fuel pump.

Moreover, fuel lines can become brittle over time, due to which they can crack and cause fuel leaks after changing the fuel pump. So, when you snap all fuel lines on, make sure that they don’t have any cracks. 

Lastly, make sure to properly tighten the fuel hoses with the clamps after changing the fuel pump.

6. Inaccurate Fuel Gauge Readings Upon Pump Replacement

The fuel gauge sending unit is a small device that is located inside your fuel tank. This unit comes with a fuel pump assembly.

Its primary function is to measure the amount of fuel in your tank and send that data to your dashboard. This allows you to see how much gas you have left and when you need to fill up.

When the fuel pump pressure sending unit is working correctly, your fuel gauge should reflect the correct amount of fuel in your tank. 

On the other hand, a fuel pump is a small cylindrical component you will find inside the casing of the fuel pump assembly.

If you’re just replacing the fuel pump instead of the whole assembly, the chances are that while taking the old fuel pump assembly out of the fuel tank, the electrical mechanism connected to the fuel level float arm has been damaged.

The fuel pump assembly has to be taken out at a slight angle so that the level float easily clears the opening.

Moreover, while re-installing the fuel pump assembly, make sure that the arm of the fuel level float sits in the same direction as the float arm of the previous fuel pump assembly was mounted. If you accidentally bend the float lever while installing the fuel pump, it will cause inconsistent fuel gauge readings.

If you only replace the fuel pump, and not the whole assembly, including the sending unit, the fuel gauge sending unit can damage due to high heat if the fuel level becomes less than 25% of the capacity of the fuel tank.

Common Problems After Changing Fuel Pump: FAQs