How to Bleed Fuel System and When Will You Need This?

Your engine will need fuel to function. Therefore, a vehicle's fuel system keeps the fuel on hand and supplies it to the engine to power your car. The fuel system acts like our body's vascular system. It's a vital component. Sadly, foreign objects like air can get into the fuel system. The air causes airlocks within the fuel system, which damages or reduces engine performance.

The airlocks often occur if you've been driving it for a while. Foreign interference may lead to issues like engine stalling, rough idling, and poor performance. Hence, it's vital to bleed the fuel system regularly to prevent these problems. 

Today's guide will cover how to bleed the fuel system and when to purge it. So, let's get working on your fuel system. 

What's the Fuel System in Your Vehicle?

Your fuel system contains storage, filtration, and delivery components. They help push fuel to the engine. The gasoline tank, fuel pump, fuel filter, fuel injectors, and fuel lines act as the major components of a fuel system. The fuel pump will draw fuel from the tank. It then delivers it to the fuel filter. 

The fuel filter will eliminate contaminants like dust particles and transport the clean fuel to the filter. The fuel lines will then transport the clean fuel to the fuel injectors. The injector, in turn, sprays the fuel into the engine's combustion chamber.

Each component should work as expected to ensure clean fuel moves to the engine. Therefore, you will need a regular maintenance schedule to keep these components working. 

Why Do We Bleed the Fuel System?

Your engine will need an appropriate mix of fuel and air to run smoothly. Sadly, air might end up in the fuel system in several ways. The most common entry point is when changing the oil filter, when the car runs out of fuel, or when a fuel line is damaged.

The air may lead to issues like rough idling, stalling, and poor performance because it will prevent fuel from getting to the engine. Therefore, it may starve the engine. It's wrong to starve the engine because it damages it. Any damage to the engine will require costly fixes or replacement. 

Bleeding the fuel system prevents these problems. It is part of your vehicle's maintenance routine. You should do it regularly. The whole process entails removing any airlock within the fuel line. The bleeding will keep the engine performing optimally because it cleans the fuel system. It will eliminate airlocks from the entire fuel system and fuel lines. Therefore, it restores the smooth flow of fuel to your engine. 

When To Bleed the Fuel System?

You'll have to bleed the fuel system when you notice the following symptoms.

• A rough engine. Airlocks often cause the engine to accelerate erratically or stall. It can also result in an idling car.
• A pungent smell may emerge from the exhaust pipe.
• Poor fuel economy.
• You may have seen black smoke from your tailpipe. It occurs when climbing a hill or accelerating.
• It may cause a misfire.

All these issues arise due to airlocks within the fuel system. They interfere with the flow of fuel, which causes rough performance as you drive your car. Restore the fuel flow within the fuel system and lines to solve the above issues. That's why it's good to bleed the fuel system because it keeps the entire system clean.  

Airlock Causes

Different issues can cause airlocks within the fuel system. Let's look at these issues in detail. 

Replacement of the fuel filter- The fuel filter is a crucial part of the fuel system. It's vital to keep it clean and replace it regularly. The replacement procedure opens the fuel system susceptible to air entry. You may also need a fuel pump bleed after changing the fuel filter. 

Fuel Tank Replacement- You may need to replace the fuel tank after driving your car for a long time. Sadly, air may escape into the fuel system as you install a new fuel tank. Therefore, you'll need to bleed the fuel system after installing the new tank to remove any air that may have entered the fuel system during the replacement process.

Running out of Fuel- Air may enter the fuel system if your car runs out of fuel since it may take some time to reach the engine as you add more fuel to the tank. The process may make your fuel system susceptible to airlocks. You may notice that your engine sputters or misfires. Therefore, you may have to eliminate the air from the fuel system by doing a fuel bleed.

Fuel Line Damage- Air may get into your fuel system if you have damaged fuel lines. Therefore, you'll have to fix the fuel lines to prevent airlocks in your fuel system. 

A Leak in the Fuel Pump- A leaking pump will allow air to access the car's fuel system. The leak may cause air locks within the fuel system. 

You risk poor engine performance when air gets into the fuel system. So, you may have to fix any damaged component within the fuel system. Also, consider purging the fuel system to prevent air from getting into the fuel system. 

Steps to Bleed the Fuel System

The process of bleeding the fuel system may be complicated. Therefore, it is crucial to consult your owner's manual for detailed instructions because the process may differ based on the type of fuel system in your car. Alternatively, you can talk to your mechanic if you don't feel confident to do the bleeding yourself. 

Here are the general steps to take when doing a fuel system bleed.

1) Locate the fuel system

Start the bleeding process by locating the fuel system's components. You will need to find the fuel lines, fuel injectors, fuel tank, fuel pump, and fuel filter. You may also need to remove a cover or panel to get to certain parts.

2) Release the fuel system's pressure

You should release the pressure in your fuel system before completing any repair procedures to avoid errors. Find and remove the fuel pump fuse or relay to release the pressure. Do this if you have been experiencing a stalling engine.

You may have to release the fuel pressure when the engine stalls. Release the pressure and restart your automobile. You can also use a fuel pressure gauge to lower the pressure by depressing the valve if the fuel rail of your car includes a Schrader valve.

Do that to a point where the fuel pressure releases more fuel. Always consult the owner's manual for detailed instructions on how one frees the fuel pressure before attempting it.

You may need to check if you leak. 

3) Find the bleeding screw

You will see a bleeder screw on the wheel cylinder or brake calliper. It is a tiny, threaded screw you can remove using a socket or wrench. The bleeding screw guarantees that the brake system operates properly by releasing air from the brake lines. Consult the owner's manual or a maintenance manual for your vehicle make and model to find the location of the bleeder screw. 

4) Prepare the fuel system

Ensure you have enough fuel in the fuel tank before bleeding the fuel system. Loosen the vent screw on the gasoline filter to allow air to escape. The next step is to find the bleed screw on the fuel injection pump or fuel rail and get a container ready to catch the bled fuel. Open the bleed screw and pump the hand primer. Finally, tighten the vent and bleed screws before starting the engine to check the fuel flow.

5) Drain the Fuel System

It's time to bleed the fuel system after you've readied it and identified the bleeder screw. You'll need to prepare for a messy process as you purge the system. 

Use a wrench to remove the bleeder screw and allow the fuel and air to escape. Keep turning the screw until nothing but fuel comes out. Ensure you have enough rags or absorbent cloth to absorb the mess as you purge the system. The system is cleansed of air if you only see air coming out of the bleeder screw. Tighten the bleeder screw once all the air has been drawn out of the system. If the airlock persists, bleed the fuel filter or the injector pump.  

Once the screw is tight, move to the next step. 

6) Start the Engine

Starting the engine is necessary after bleeding the fuel system. As the gasoline pump primes the system, turn the key to the "On" position and wait a few seconds. Once the engine is running, stop it. 

Take your car to the road and test whether there is improved engine performance. 

Wrapping Up

It's vital to bleed your fuel system regularly. The process keeps the fuel system clean and free from airlocks. Therefore, you will notice optimal engine performance when you bleed your fuel system. 

As we've mentioned above, the process may be complicated. Therefore, work with your mechanic to avoid damaging any component within the fuel system.