Replacing Fuel Lines: A Step-By-Step Guide For Your Car

Replacing the fuel lines in your car is a repair job that can be done at home with a basic set of tools and some automotive know-how. The parts are inexpensive, and you can save hundreds of dollars on labour and other charges by doing the work yourself. However, it's important to note that working with fuel lines can be dangerous, and safety precautions must be taken to avoid accidents. Before starting, it's recommended to relieve the fuel pressure by locating and removing the fuse or relay for the car's fuel pump. This will depressurise the fuel lines and reduce the risk of fuel spraying everywhere when the hoses are removed.

How to Replace the Fuel Lines in Your Car

Emptying the fuel line

The first step in replacing your car's fuel line is to empty the fuel line. The location of the fuse box in your car will depend on the model but they are normally located under the passenger side glove box. If you are uncertain where the fuse box is, refer to the vehicle’s owner handbook. When you locate the fuse box, remove the fuse for the fuel pump. It should be clearly labelled. Once you have removed the fuse, start the car and let it burn up the rest of the fuel in the fuel line.

It is important to relieve the pressure in your fuel system. Most cars today use fuel injection, which sprays fuel into the combustion chamber at incredibly high pressures. If you do not relieve this pressure, gasoline will spray everywhere when you start removing the fuel hoses from the filter.

To relieve the pressure, 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 or relay. 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 an electric spark as you work, disconnect and isolate the negative terminal on your car's battery.

Finding the fuel line

Before you can replace the fuel line, you need to find it. The fuel line in your car connects the fuel tank to the fuel pump, and then to the engine's combustion chamber. It is usually located in the engine bay under the hood, but can also be found in the rear of the vehicle near the gas tank.

To find the fuel line, first, empty the fuel line by locating and removing the fuse for the fuel pump in your car's fuse box. Then, start the car and let it burn up the remaining fuel in the line. Once the line is empty, open up the engine space and locate the fuel line. It is a cylindrical part, and the fuel hoses are the tubes that run into it.

Follow the line to the other end, which can be tricky as it will disappear from sight. To make this easier, you can use a straightened-out wire hanger with some bright material on the end. You should also jack up the car at this point so that you can crawl under it, using a set of jack stands for safety.

The fuel line will be locked in place by a set of holders that are screwed or bolted onto the car. Remove the connection to the engine compartment first. You may need to use a special solvent on the fittings to get them off easily.

Removing the fuel line

Before you begin, ensure you have all the necessary tools and materials to complete the job efficiently. These include a flathead screwdriver, a fuel hose quick disconnect kit, fuel-resistant gloves, a fuel transfer tank with a pump, and a ratchet with metric and standard sockets. It is also important to work in a well-ventilated area, have a fire extinguisher nearby, and wear protective clothing and nitrile gloves.

First, locate your car's fuel lines and fuel filter. The filter is typically in the engine bay under the hood, but it can also be in the rear of the vehicle near the gas tank. The fuel lines are the tubes that run into the filter.

Next, relieve the pressure in your fuel system. Find the fuse box and locate the fuel pump fuse or relay. Start the car, and while the engine is running, remove that fuse or relay. The engine should shut off within a few seconds, and the fuel system will no longer be pressurised.

Now, disconnect and isolate the negative terminal on your car's battery to avoid any chance of an electric spark.

If your car is an older model with a fuel hose in the engine compartment, locate the damaged or leaking fuel hose and remove the hose clamps holding it in place. Place a drip pan underneath, then pull the hose off the attaching fuel line, fuel pump, or carburetor. Clean the surface where the fuel hose attaches with a lint-free cloth.

For newer vehicles with a fuel hose in the engine compartment, use a fuel hose quick disconnect tool to remove the hose from the fuel rail and the fuel line behind the engine along the firewall.

If your car has a fuel hose under the vehicle, you will need to remove the fuel tank straps and lower the fuel tank to access the fuel hose. Use a transmission jack or similar to support the fuel tank. Remove the mounting bolts from the fuel filler neck, then lower the tank enough to access and remove the fuel hose.

Now, carefully remove the fuel hose from the fuel pump and fuel line. Use a quick disconnect tool if necessary. Be cautious when removing plastic fuel lines as they may break easily.

If your vehicle has an inline fuel filter, use a quick disconnect tool to remove the fuel line from the filter.

Finally, if you are removing all three lines (supply, return, and vapor), you will also need to disconnect the vapor line from the charcoal canister and the return line from the fuel tank using a quick disconnect tool.

Placing the new fuel line

Now that you've successfully removed the old fuel line, it's time to install the new one. If you purchased a new fuel filter, now is the perfect time to install it as well. Begin by sliding the new hose clamps over the new fuel line. Ensure the clamps are loose for now, as you'll need to adjust them later. Next, slide the open ends of the new fuel line into place and check the fit.

It's important to ensure that the new fuel line is neither too long nor too short. If there are any kinks or bends in the line, the gasoline may not flow properly. If the new line is too long, cut a small portion off the ends with a knife until you achieve the perfect fit. Once you're happy with the length, tighten the clamps with a screwdriver until the line is firmly in place.

Now, reconnect the negative terminal on your car's battery and then pressurise the fuel system by returning the fuel pump fuse in your car's fuse box. Try starting the engine. It may take a few seconds for the fuel to flow through the system, but if you've followed the steps correctly, the engine should be running normally again.

Inspect your work for any fuel leaks while the car is running. If you do find a leak, shut off the engine and repair the issue immediately. Remember to follow the safety precautions outlined earlier in this guide.

Finally, you'll need to reset all the settings in your vehicle, such as your radio, electric seats, and electric mirrors, unless you used a nine-volt battery saver during the process.

Checking for leaks

Once you've replaced your fuel lines, it's important to check for any leaks. Here's a step-by-step guide:

Step 1: Reconnect the battery

First, reconnect the ground cable back onto the battery's negative post. Remove any battery savers you used during the replacement process. Tighten the battery clamp up tight and ensure that the connection is good.

Step 2: Turn the ignition key on

Turn the ignition key on and listen for the fuel pump to activate. Then, 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.

Step 3: Check for leaks

Use a combustible gas detector to check all of the connections for any leaks. Also, sniff the air for any fuel odours. If you detect any leaks, shut the car off and repair them immediately, taking the necessary safety precautions.

Step 4: Lower the vehicle

Use a floor jack to lift the vehicle at its specified jacking points until the wheels are completely off the ground. Then, remove the jack stands and lower the vehicle so that all four wheels are on the ground. Finally, remove the wheel chocks.

Step 5: Test drive the vehicle

Drive the vehicle around the block, going 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.

Frequently asked questions