Inside Your Car 30 September 2022

Fuel pumps: Everything you need to know

It’s easy to take your fuel pump for granted, but if you’re experiencing a lack of power in your car, or worse - it’s not starting, then you might need to get it tested.

It’s a pretty important part, as it’s responsible for making sure that fuel is delivered to your engine at the correct pressure.

So how does it work, and how can you test it if you suspect a problem?

What does a fuel pump do?

Everyone knows that petrol powers your car, but to understand how it gets from the fuel tank to the engine, you need to look at the fuel pump amongst other things.

Housed within the fuel pump module, which normally sits inside the fuel tank, this little motor is essential for getting the right amount of fuel to the engine at the right time. If it isn’t working properly, your car won’t have the power it needs and may even stop altogether.

The fuel pump is a hard-working component, so it’s important to make sure it’s in good condition.

How fuel pump works

In modern engines, fuel pumps are electric motors that move the fuel under high pressure to the fuel injectors. They’re the heart of the fuel assembly, which is the system that filters the petrol, as well as monitors how much you have left in the tank.

When you put your key in the ignition, the petrol is pumped from the tank into the fuel assembly via a filter sock that removes large particles. It then goes into the fuel pump which pumps it out under the correct pressure, and through a finer filter that removes impurities before it heads to the engine. It’s a bit more complex than this, but that’s basically how it works.

If the fuel pump stops working or gets clogged, it can cause lots of problems with performance as there won’t be the correct amount of fuel coming through to run the engine.

What are the signs your fuel pump is going out?

Your fuel pump can go bad for lots of reasons—contaminated fuel can cause it to clog or fail all together, a faulty fuse can cause it to temporarily not operate (pending fuse replacement), or it can simply burn out from normal wear and tear.

To prevent further damage to your car, bring it to mycar if:

Your car lacks power going uphill or carrying heavy cargo.
It won’t start, or takes a few cranks to start.
Your car almost stalls when accelerating from a stopped position.
Your car suddenly surges while you’re driving.
Your car’s engine sputters at high speeds.
You hear a whining noise coming from the fuel tank.
The fuel pump isn’t making a sound when you turn the key. It will usually make a humming noise under the back seat where it’s located when you start the ignition.

If you’re experiencing any of these issues, it’s time for a fuel pump test.

How to test a fuel pump

Besides taking note of the issues above, there’s a couple of things you can do to test the pump to get a better idea as to whether you need to bring it in for repair.

A good first step is checking your fuses, as a faulty fuse can stop the pump getting power. Check your owner’s manual to find out where this is located, and take out the fuel pump fuse to see if it’s blown. If it is, you’re lucky as they only cost a few bucks to replace and you can do it yourself.

If you have a fuel pump pressure gauge and your car has a testing port on the injector rail, you can also check the fuel pressure. Attach the gauge to the testing port, and have someone start the car and rev it. Note the pressure (if any), and compare this against the correct pressure noted in your user’s manual.

What happens when a fuel pump goes bad?

When a fuel pump goes bad, it can’t provide the right amount of fuel to the fuel injectors. Your car won’t drive right and may stop altogether.

By bringing it in for repair or replacement, the mechanic can perform further diagnostic tests and remove the fuel filter assembly to have a better look at what needs replacing.

Can you drive with a failing fuel pump?

It’s not a good idea to drive with a failing fuel pump, as having too little fuel coming into your injectors can heat up your engine, and burn out your pistons and catalytic converter—which means in the worst case, your engine could go kaput. Not to mention surges in power from erratic fuel supply can also be dangerous while you’re driving and potentially cause an accident.

This is why it’s a good idea to bring it into your local mycar mechanic if you notice any of the above signs, for safety and peace of mind.

So don’t delay - make an appointment with one of our experienced mechanics and we’ll have you safely on your way in no time!