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Can a Bad Fuel Pump Cause a Misfire? (Answered)

If you are familiar with a vehicle or car, you might know about the fuel pump and its problems. Generally, the fuel pump is one of the essential and sensitive parts of your vehicle. So, if the fuel pump has a problem, it can decrease the overall performance of the vehicle.

So, you might be confused about whether a bad fuel pump can cause a misfire or not. Generally, a simple problem in one component of your car might lead to a bigger problem. So, you have to know details about a fuel pump and the consequences of a bad fuel pump.

Can a bad fuel pump cause a misfire?

A bad fuel pump can cause a misfire. Even a little bit of problem in the fuel pump can cause a misfire. Because the fuel pump in the vehicle is a sensitive component. Generally, a bad fuel will not provide adequate pressure. This can lead to various problems. Moreover, it can cause a misfire.

The fuel pump is one of the most important parts of the fuel system. Because a fuel pump helps the fuel system to maintain pressure to supply adequate fuel to the fuel injector.

So, if there is a problem with the fuel pump, the whole fuel system and the engine will be affected. For example, it can cause a misfire.

When a bad fuel pump affects the fuel system, it can cause an engine to misfire at startup. Moreover, if the situation is too bad, it can cause a misfire on one cylinder. Sometimes, a bad fuel pump will cause a random misfire.

So, whenever you experience any misfire, you have to assume that there might be a problem with the fuel pump. Moreover, many faulty signals can be induced with a bad fuel pump.

Generally, an electric fuel pump is common in all cars nowadays. But a bad fuel pump is unable to provide sufficient pressure to the fuel injector. As a result, the cylinder or fuel tank will not produce adequate power to start the engine.

So, the overall performance of the vehicle will be hampered. That’s why a bad fuel pump will cause a misfire in the engine or the cylinder.

Can a bad fuel pump cause a misfire on one cylinder?

Yes, a bad fuel pump can cause a misfire on one cylinder. Generally, two fuel injectors or separate injectors can inject fuel to a separate cylinder. So, a problem in one injector can cause a problem with the corresponding cylinder.

If a bad fuel pump is present in the fuel system, it will supply lean or insufficient pressure to the fuel injector.

As a result, that fuel injector will be affected and will not inject enough fuel into the cylinder. That means the corresponding cylinder will not get enough power to start the engine.

That’s why a misfire can occur on one cylinder. So, bad fuel can be responsible for a misfire on one cylinder.

How does a bad fuel pump cause misfire?

From the fuel pump to the engine, all parts are interconnected. So, a problem in one component will affect the others. Sometimes, a problem might be avoided. But a fuel pump is a complex and sensitive part. So, a fuel pump must have to be good to avoid misfire.

Generally, if there is a problem in the fuel pump, or the fuel pump is bad, it will not generate enough pressure to supply fuel to the engine by the fuel injector. The fuel injector will not get enough fuel to supply to the engine. That means there will be less power from the fuel pump to the fuel injector.

Ultimately, the engine will not start properly. A problem to start the engine or insufficient power to start the engine is called a misfire. So, thus a bad fuel pump causes a misfire.

What problems can a bad fuel pump cause?

A bad fuel pump can cause different problems to the different components of the vehicle. For example, it can cause problems from the fuel system to the engine and the overall performance. So, let’s see what problems a bad fuel pump can cause.

Misfire:

You might know that a bad fuel pump can cause a misfire. This misfire can be at the cylinder or the engine. That means the cylinder or the engine will not get enough energy to start and lead to random misfires.

Problems with starting:

When there will be a problem with the engine, the engine will not start well. So, bad fuel is responsible to cause less fuel in the engine. So, the engine will face difficulties starting.

Loss of power:

A bad fuel pump will cause a loss of power in the vehicle. Even when the vehicle is running, a loss of power might occur. Generally, you will notice the loss of power while at a high speed or climbing a high place.

Poor mileage:

A bad fuel pump will also cause poor gas mileage. The poor supply of pressure of a bad fuel will create this problem.

How to test if the fuel pump is bad?

When you face a problem with your car suddenly, you can’t find immediately what is wrong. So, you have to investigate or test the fuel pump whether it is bad or not. So, let’s see how you can test if the fuel pump is bad or not.

Listening test:

The simplest and initial step is the listening test. You will need another person to help with hearing or starting the engine.

While one will start the engine, another can hear the sound of a fuel pump from the rear seat. If the fuel pump is good, you will hear a sound while starting the engine.

Checking the fuel pressure:

You can check the fuel pressure and ensure that there is a problem with the fuel pump. Because bad fuel pumps lower that pressure or fluctuate the pressure. You can measure the pressure with a fuel pressure gauge.

Checking the fuel filter:

Then you have to check the fuel filter. Generally, the fuel filter keeps the fuel pump prevented from contamination. Sometimes, the fuel filter gets clogged and makes the performance of the fuel pump decrease.

Checking the fuses:

You have to check the fuses of the fuel pump. If you remove the fuses of the fuel pump, you will see burnt fuses. That means the fuel pump fuses are bad and the fuel pump is not working well.

Can you drive with a bad fuel pump? What happens if you drive with a bad fuel pump?

Yes, you can drive with a bad fuel pump. Because sometimes, a bad fuel pump will create difficulty to start the engine but will not stop the engine. So, you can drive with a bad fuel pump. But driving with a bad fuel pump is not recommended.

Because if you drive with a bad fuel pump, the fuel pump might stop working in the meantime. This can lead to a dangerous accident.

For example, if the engine stops while driving, the power steering and the brakes will be lost. So, these can lead to a dangerous incident. So, don’t drive with a bad fuel pump.

How to start a car with a bad fuel pump?

Generally, you should not drive with a bad fuel pump. But sometimes, you might need to start the car for an emergency. So, let’s see how you can start a car with a bad fuel pump.

  • Stop the car and leave the car to let the engine cool down.
  • Wait at least 30 minutes to cool down the engine completely.
  • When the engine is cool, the fuel pump will get time to reset itself.
  • Then you can start the car again.
  • If you want to start your car without a fuel pump, attach a fuel pressure gauge directly onto the engine that will start the car.

Can a bad fuel pump relay cause misfire?

Yes, a bad fuel pump relay can cause a misfire. Generally, a fuel pump relay is an electrical device that operates like a monitor. This relay will turn on when the ignition is on and will turn off when the engine is off.

So, if a fuel pump relay is bad, it will mislead the fuel pump. So, a fuel pump will also act as a bad fuel pump and cause a misfire. So, a bad fuel pump relay is also dangerous.

Final Thoughts

A bad fuel pump can be disturbing for driving a vehicle. Generally, a bad fuel pump will not provide enough power to the fuel injector and cylinder. So, it will cause a misfire of the engine or the cylinder. Moreover, the starting of the vehicle will be difficult and a misfire can be dangerous.