Replacing Fuel Lines: A Step-By-Step Guide For Safety

Changing a fuel line is a complex process that requires careful preparation and a good understanding of car mechanics. Fuel lines are tubes that carry fuel from the tank to the engine's combustion chamber. Over time, these lines can become damaged or corroded, leading to fuel leaks. While it is recommended that a professional mechanic carries out repairs, it is possible to change a fuel line yourself if you have the right tools and safety equipment. This includes eye protection, gloves, a fire extinguisher, and a well-ventilated workspace. Before starting work, it is essential to relieve the pressure in the fuel system and disconnect the battery to avoid the risk of sparks. The old fuel line can then be removed, and a new line installed, taking care to ensure the correct size and type of hose is used.

Identify the type of fuel line

Fuel lines are the rubber, metal or plastic pipes through which gasoline passes from the fuel tank to the fuel pump, and then into the engine's combustion chamber. There are several types of fuel lines, and they vary in terms of material, durability, pressure capacity, and ease of installation.

Rubber fuel hoses with adhesive liners are more common in older vehicles and diesel industries. They are the best choice when it comes to adjusting a fuel hose that needs to be moved frequently. However, they are not as durable as other options and may not be suitable for high-pressure applications.

Plastic hoses, also known as carbon fibre hoses, are the most common type used in modern vehicles. They are highly durable and can withstand pressures up to 250 pounds per square inch (psi). Plastic hoses help keep the fuel cool for optimal performance and reduce vapour formation. However, they are prone to breakage if subjected to movement or bending.

Steel and aluminium hoses, also referred to as fuel lines, are found in both older and newer vehicles. They are extremely durable and can handle pressures up to an impressive 1,200 psi. Nevertheless, they are susceptible to bending and kinking, which can cause a restriction and lead to pressure spikes beyond 1,200 psi, resulting in line rupture. Additionally, these lines can heat up in hotter climates, causing the fuel to boil.

When identifying the type of fuel line, it is important to consider factors such as the vehicle's age, the material of the existing lines, and the specific requirements of your repair or maintenance project.

Prepare your car for a fuel line change

Prepare your car for a fuel hose change

Before you begin the process of changing your fuel line, there are several steps you should take to prepare your car. Firstly, park your vehicle on a flat, hard surface and engage the parking brake. This will ensure your car doesn't move while you're working on it. Next, place wheel chocks around the front tires, as the rear of the vehicle will be lifted.

Now, using a floor jack, lift the vehicle at its specified jacking points until the wheels are off the ground. You can then place jack stands under the jacking points and lower the vehicle onto them. For most modern cars, the jacking points will be on the pinch weld, just under the doors along the bottom of the car.

To keep your computer live and your settings current, install a nine-volt battery saver into your cigarette lighter. If you don't have one, that's okay, but you'll have to reset your settings after.

Now, open the vehicle's hood and disconnect your battery. Take the ground cable off the battery's negative post to disable the power to the ignition and fuel system.

At this point, you should locate your car's fuel lines and fuel filter. The filter is most likely in the engine bay under the hood, but it may also be in the rear of the vehicle near the gas tank. The fuel lines are the tubes that run into the hard, cylindrical fuel filter. If you're unsure, consult your auto maintenance repair manual or ask a technician.

The next step is crucial: you must relieve the pressure in your fuel system. Most cars today use fuel injection, which sprays fuel at incredibly high pressures. If you don't relieve this pressure, fuel will spray everywhere when you start removing the fuel lines from the filter. To do this, locate your car's fuse box and find the fuel pump fuse or relay. Start the car, and while the engine is running, pull out the fuse. If done correctly, the engine will shut off within a few seconds, and the fuel system will no longer be pressurised.

Finally, to avoid any chance of a spark while you work, disconnect and isolate the negative terminal on your car's battery.

Remove old fuel lines

Before removing the old fuel lines, make sure you have prepared your car for a fuel hose change. This includes relieving the pressure in your fuel system and disconnecting the negative terminal on your car's battery to avoid any chance of an electric spark.

Now, get underneath the car and locate the fuel filter. Remove the plastic shield that surrounds it and place a catch pan or a towel underneath to catch any leaking gasoline.

Using a screwdriver or a wrench, loosen the hose clamps until they slide back and forth. Keep your pan or rags handy because gasoline could leak out of the hose. Once the clamps are loose, you should be able to remove the fuel hose. If not, use a blade to free it.

Locate and remove the other end of the old fuel hose. You should be able to pull it out with a little effort. Be sure to consult your vehicle service manual for information and tips specific to your car's fuel line. Every car is different, and there may be more than one fuel hose to remove.

If you have an older vehicle with a fuel hose under the vehicle, you will need to remove the fuel hose from the supply side of the fuel pump. Go under the vehicle and remove the fuel steel line, which may be held up by rubber grommets. Place a transmission jack or similar jack under the fuel tank and remove the fuel tank straps.

For vehicles from 1996 to the present with a fuel hose in the engine compartment, locate the damaged or leaking fuel hose and use a fuel hose quick disconnect tool to remove it from the fuel rail. Then, remove the hose from the fuel line using the quick disconnect tool.

If you have a vehicle with a fuel hose under the vehicle, use a quick disconnect tool to remove the fuel line from the fuel filter. Then, place a jack under the fuel tank and remove the fuel tank straps and mounting bolts to the fuel filler neck. Lower the fuel tank and remove the fuel hose from the fuel pump.

Note: Be careful when removing plastic fuel lines as they may break easily.

Purchase and attach new fuel lines

Before purchasing new fuel lines, it is important to identify the type of fuel hose your vehicle requires. Fuel hoses come in different materials, such as rubber, metal, or plastic, and their placement varies depending on the vehicle's make, model, and year. It is recommended to replace the fuel hoses with original manufacturer equipment (OEM) to ensure proper alignment and fit. Aftermarket fuel hoses may not fit correctly and could cause issues with the quick disconnect fittings.

You can buy replacement fuel hoses online or at a store specialising in vehicle maintenance. When purchasing, make sure to specify your vehicle's make, model, and year to ensure you get the correct size. Along with the fuel hoses, you will also need to buy fuel hose clamps, which are metal rings that tighten to hold the hoses in place and prevent leaks.

Once you have the new fuel lines, it's time to install them. Put the new hose clamps over the new fuel line, but keep them loose for now. Ensure that the hardware will face you when the line is in place, making it easier to tighten the clamps later. Slide the open ends of the fuel hose into place and check the fit. Make sure the hose is not too long or too short, and there are no kinks or bends that could restrict fuel flow.

If the new hose is too long, remove it and use a knife to cut off a small portion from the ends until you achieve the perfect fit. Once you are satisfied with the length and placement, tighten the clamps with a screwdriver until the hose is firmly in place. Now, reconnect the negative terminal on your car's battery and pressurise the fuel system by returning the fuel pump fuse in your car's fuse box.

Finally, start the engine. It may take a few seconds for the fuel to flow through the system, but if you have followed the steps correctly, the engine should run normally. Inspect your work for any fuel leaks while the car is running, and if you notice any leaks, shut off the engine and repair them immediately, following the necessary safety precautions.

Check for leaks

Once you've replaced your fuel line, it's important to check for leaks. Here are some detailed, step-by-step instructions to help you do this safely and effectively:

Firstly, reconnect the ground cable back to the battery's negative post. Remove any battery savers you may have used. Tighten the battery clamp and ensure a good connection. If you didn't use a battery saver, you'll need to reset all your vehicle's settings, such as your radio, electric seats, and mirrors.

Next, turn the ignition key on. Listen for the fuel pump to activate and turn off the ignition after the fuel pump stops making noise. You will need to cycle the ignition key on and off 3 to 4 times to ensure all the fuel lines are full of fuel.

Now, use a combustible gas detector to check all the connections for any leaks. Also, sniff the air for any fuel odours. If you smell fuel, you are smelling vapours that are very flammable, so do not smoke around the vehicle.

After you've checked for leaks, it's time to lower the vehicle. Use a floor jack to lift the vehicle at its specified jacking points until the wheels are off the ground. Remove the jack stands and keep them away from the vehicle. Lower the vehicle so that all four wheels are on the ground, then pull out the jack and put it aside. Finally, remove the wheel chocks.

Finally, take your vehicle for a test drive. Go over different bumps to allow the fuel to slosh around inside the fuel lines. Monitor the dashboard for the fuel level and for any engine lights to appear. If your engine light comes on, there may be a further issue with the fuel system or an electrical problem. If the problem persists, seek help from a certified mechanic.

Frequently asked questions