Replacing Stihl Weedeater Fuel Line: A Step-By-Step Guide

The fuel lines on Stihl engines contain a main or suction hose and an impulse or return hose. The lines age quickly and must be replaced almost every season. Clogged or dirty fuel lines are a common cause of engine problems. Changing the fuel line on a Stihl FS90 trimmer weedeater can be difficult as the fuel line is separated by a connector on the fuel tank. This can be done by removing the carburettor, spraying the connector with WD-40, and carefully prying up the tab until it pops out.

Drain old fuel into an approved container

To drain the old fuel from your Stihl weedeater into an approved container, you will first need to open the fuel tank cap. This will allow you to access the fuel and begin the draining process. Once the cap is open, you can start transferring the old fuel from the tank into your approved container.

It is important to use an approved fuel container to capture the drained fuel. This is for safety reasons and to ensure that the fuel is disposed of or stored correctly. Approved fuel containers are designed to safely hold flammable liquids and have specific features, such as proper ventilation and a tight seal.

Make sure you are wearing appropriate protective gear when handling fuel, such as gloves and eye protection. Work in a well-ventilated area to avoid inhaling fumes.

The next step is to locate the fuel filter, which is positioned at the bottom of the tank. Using a metal hook, carefully pull the fuel filter upward and then remove it from the end of the suction hose. This will allow you to access the fuel lines and continue the process of changing the fuel lines on your Stihl weedeater.

By following these steps, you will be able to safely and effectively drain the old fuel from your Stihl weedeater, preparing you for the next steps in the fuel line replacement process.

Remove the fuel filter

To remove the fuel filter from your Stihl weedeater, you'll first need to open the fuel tank cap. If the tank still has gas inside, siphon it into an approved container. The best time to perform this procedure is just before the weedeater runs out of fuel.

Now that the tank is empty, you can reach inside and remove the fuel filter. Form a hook at the end of a 12-inch piece of 12- or 14-gauge wire. Electrical wire works well for this, but be sure to strip off the insulation to avoid contaminating the gas tank. Reach the wire into the tank, hook it around the filter, and pull the filter out. You may need a flashlight to help you see inside the tank.

Once you've hooked the filter, hold the fuel line firmly with one hand while you work the filter off with a flat-head screwdriver. Don't let the fuel line fall back into the tank after you remove the filter, as it will be difficult to retrieve without the filter on the end. With the filter removed, you can now work on replacing the fuel line.

Disconnect the air filter

To disconnect the air filter on your Stihl weedeater, start by removing the cover or housing that protects the filter from dirt, dust, and debris. This cover is typically located on the side of the weed eater and can be easily unscrewed or popped off. Depending on the model, you may need to use a screwdriver to loosen the screws or release the clips holding the cover in place. Be sure to pay attention to how the cover is oriented so that you can replace it correctly later.

Once the cover is removed, carefully remove the air filter. Take note of the orientation of the filter to ensure you can put it back correctly. Inspect the air filter for any visible dirt or debris. If it appears dirty or clogged, it's time to give it a good cleaning.

To clean the air filter, start by gently tapping it on a hard surface to dislodge any loose dirt or debris. You can then use compressed air or a soft brush, such as a toothbrush, to remove any remaining dirt from both sides of the filter. Be careful not to damage the filter material or tear it. After cleaning, inspect the filter for any tears or damage, and replace it if necessary.

By regularly cleaning and maintaining your Stihl weedeater's air filter, you can improve its performance, increase its lifespan, and prevent engine damage. The air filter plays a crucial role in preventing dirt, dust, and debris from entering the engine, which can cause reduced performance and even engine failure if left unchecked.

Unhook the throttle cable

To unhook the throttle cable on your Stihl weedeater, you'll need to access the carburetor. Start by locating the choke cover plate on top of the carburetor and removing it. Once the choke cover plate is off, you'll be able to access the throttle cable.

Before you begin, ensure the weedeater is switched off and that you are wearing protective gear, including gloves and eye protection. It is also recommended to drain any remaining fuel into an approved fuel container.

Now, carefully unhook the throttle cable from the choke cover plate. You may need to use a screwdriver to release any clips or fasteners holding the cable in place. Be gentle, as the cable is vital to the machine's performance. Once the cable is loose, carefully set it aside, ensuring it doesn't get tangled or caught on any other components.

At this point, you can begin the process of replacing the fuel line. It is important to ensure that the new fuel line is compatible with your Stihl weedeater model. Refer to the user manual or seek advice from an authorised Stihl dealer if you are unsure.

Finally, remember to dispose of the old fuel line responsibly and according to local regulations.

Remove the fuel return hose

To remove the fuel return hose on your Stihl weedeater, you'll need to first open the fuel tank cap and drain all the old fuel into an approved container. This is an important safety step to avoid any accidents or spills. Once the fuel is drained, use a metal hook to pull the fuel filter at the bottom of the tank upwards and then pull it off the end of the suction hose.

The next step is to remove the air filter's cover and unhook the air filter. You'll then need to remove the two mounting screws that are holding the air filter box in place. With the air filter box removed, you can now access the fuel lines.

The fuel return hose is the impulse or return hose, which returns excess fuel back to the tank. To remove it, simply pull it off the stub next to the spacer flange using your fingers. Be careful not to spill any remaining fuel. With the fuel return hose removed, you can now replace it with a new one, following the manufacturer's instructions.

It is important to note that the fuel lines on a Stihl engine age quickly due to fuel impurities and should be replaced almost every season. By replacing the fuel lines, you'll help ensure that your engine runs smoothly and avoid common engine problems caused by clogged or dirty fuel lines.

Frequently asked questions