Fuel Pump Won't Turn On with Ignition: Looking for the Reason

Starting your car is as simple as turning the key in the ignition or pushing the start button. However, there are a lot of steps that go into making sure your engine starts. Before the engine can crank, the fuel pump needs to turn on and move fuel from the tank to the combustion chamber. A common cause of cars not starting is when the fuel pump fails to turn on with the ignition. What could be the reason for this?

When the fuel pump doesn't turn on with the ignition, it indicates that there is a problem with the fuel pump itself or the electrical system that powers it. There could also be a problem with the fuel filter.

In this article, we'll take a look at the reasons why the fuel pump might not turn on with the ignition. We'll also discuss what you can do to get your fuel pump working again.

Why Won't My Fuel Pump Turn On?

The function of a fuel pump in an engine is pretty straightforward. The fuel pump moves fuel from the fuel tank to the engine. Without a working fuel pump, there's no way for the engine to run or even start.

A fuel pump is a low-maintenance part that should last a long time. If your fuel pump isn't turning on, then you might be wondering what has gone wrong with it. Usually, the problem stems from another part of the fuel pump system, such as the fuel filter or the fuel pump relay. In some cases, the fuel pump might have gone bad, especially if you've been using it for more than 100,000 miles.

Let's take a look in more detail at the reasons why your fuel pump won't turn on with the ignition.

1) Bad Fuel Pump Relay

The fuel pump relay acts as a sort of switch that controls the power sent to the fuel pump. When the ignition is turned on, the fuel pump relay is activated by the powertrain control module. This turns on the pump, allowing fuel to move from the fuel pump and pressurize the fuel lines.

If the fuel relay is damaged, then the powertrain control module won't be able to activate the fuel pump. This means that no matter how many times you turn on the ignition, the fuel pump won't turn on.

To find out if your fuel pump relay is bad, you can remove it from your fuse box and inspect it. Consult the owner's manual of your car to find the location of the fuse box and the fuel pump relay. Once you've found the relay, you can remove it and shake it to see if it makes a rattling sound. A rattling noise indicates that the relay might be damaged.

You can also check for signs of physical damage like corrosion or burns.

Another way to check if the relay is damaged is to have someone start the car while you have a hand on the relay. A faulty relay will often produce an audible clicking sound or a clunking vibration.

2) Bad Fuel Pump

Fuel pump failure can happen suddenly, with little warning. Most times a faulty fuel pump will make a high-pitched whining sound as the pump motor attempts to run. In some cases, a failed fuel pump will be completely silent and might be impossible to distinguish at first glance from a pump that hasn't turned on.

If the fuel pump is faulty, you will need to have it replaced. Most modern cars use submerged fuel pumps, which are fuel pumps that are located in the fuel tanks. Replacing these types of fuel pumps requires the removal of the fuel tank. This makes fuel pump replacement a complicated process that is best left to a professional.  

3) Clogged Fuel Filter

A clogged fuel filter can result in damage to the fuel pump. The longer the fuel filter remains clogged, the more the fuel pump will strain to move fuel through the fuel system. This can cause premature wear and overheating in the pump, causing it to fail.

If the fuel filter is clogged, it simply needs to be replaced.

4) Faulty Ignition Switch

When you turn the key or push the start button in your car, it activates the ignition switch. When the ignition switch is turned on, it lets the car know that the driver wants to start the engine. This activates the necessary systems in the car, like the fuel pump and starter motor. A faulty ignition switch won't be able to send a signal to the car, and the necessary systems won't start up.

One of the best ways to tell that you're dealing with a bad ignition switch is when you notice that there is no reaction at all to turning the key. This means that both the fuel pump and the starter motor won't activate. You might also notice that turning the car to accessory mode doesn't work.

A faulty ignition switch will need to be replaced. Replacing the ignition switch is a difficult task that involves removing part of the car's interior trim, so it is recommended that you have this done for you by a professional.

5) Bad Wiring

Bad wiring in the ignition system can cause your fuel pump not to come on when you turn on the ignition. When the ignition is turned on, an electrical system is sent from the ignition switch to the powertrain control module. The powertrain control module then sends electricity to the fuel pump relay to activate the fuel pump. Faulty wiring along any of these pathways can prevent the fuel pump from receiving power when the ignition is turned on.

There are many different parts where faulty wiring could be located, so it is best to get the help of a professional automotive electrician to diagnose and repair the faulty wiring.

6) Inertia Switch

Modern cars have a safety feature called an inertia switch. This switch detects sudden deceleration and disables the fuel pump in the event of an accident or collision. This is a safety feature that turns off the electrical supply to the fuel pump in case the accident may have resulted in a fuel leak.

While this is a useful safety feature, it might activate even when it is not necessary. Minor accidents and collisions can also trigger the inertia switch, causing the fuel pump to suddenly go dead.

If you're experiencing your fuel pump troubles after being in a minor collision, then you might be dealing with an active inertia switch. Luckily, fixing this issue is very simple. By consulting the owner's manual for your car, you can find the location of the inertia switch as well as how to reset it.

How to Check if Your Fuel Pump is Turning On

If you're unsure whether your fuel pump is turning on with the ignition, you can easily check it on your own. This is a quick test that will help you determine whether your pump is actually turning on with the ignition.

There are two ways to check the pump. You can do it from inside the car, or from outside.

1) How to Check the Pump from Inside the Car

To test the pump, make sure the environment is quiet and free of distractions. You will need to focus to listen to the sound of the pump.

Turn the ignition on, but don't start the engine. If the pump is still working as it should, then it will turn on. You should be able to hear the slight whirring sound of the pump turning on, or the sloshing sound of fuel being pushed through the fuel system.

If you can't hear anything, then there is a chance that your pump is not turning on. There is also a possibility that you can't hear the sound from inside the car. To be more certain, you will need to check from outside the car.

2) How to Check the Pump from Outside the Car

Listening to the pump from outside the car is a more reliable way to check if the pump is working, but it can't be done on your own.

If you can get a friend or family member to help you for a few minutes, you'll be able to listen to the sound of the pump with more certainty.

• Remove the fuel cap.
• Put your ear close to the fuel opening to listen for the sound of the pump in the fuel tank.
• Ask your friend to turn the ignition on without starting the engine.

If the pump turns on, then you should hear a whirring sound, or some other mechanical sound indicating that the pump motor has started operating. If you hear only silence, then the pump is not turning on and you will need to fix it.

Conclusion

The fuel pump of your car should turn on once the ignition is switched on. The fuel pump refusing to come on is a serious problem that will leave your car unable to start.

This problem is usually caused by a problem with the electrical system that powers the pump. It could also be caused by a problem with the fuel system, such as a damaged pump or a clogged oil filter.