Trimmer Fuel Line Replacement: A Step-By-Step Guide

String trimmers are handy tools for lawn care and landscaping, but they can be temperamental. One common issue is a blocked, bent, or split fuel line, which prevents gas from reaching the engine. Fuel lines can also degrade over time, becoming brittle and cracking. Luckily, replacing a string trimmer fuel line is a common repair that you can do yourself with the right tools and safety equipment. This repair guide will walk you through the steps to get your string trimmer running smoothly again.

How to Replace String Trimmer Fuel Line

Removing the trimmer's fuel system

Firstly, you need to remove the trimmer's fuel system cover, which is usually located at the rear of the engine. Remove any fasteners that affix the cover to the engine so you can access the carburetor.

Next, you will need to unscrew the carburetor fasteners. The carburetor is affixed to the engine against a plate, sometimes called a carburetor choke plate. Since the entire choke plate, carburetor, and fuel tank need to be removed, release any fasteners on the carburetor.

The third step is to release the throttle cable from the carburetor. Most trimmer throttle cables thread through the carburetor choke plate and attach to the carburetor. Simply lift and tilt the carburetor to release the throttle cable.

Once the carburetor is free, the only remaining step before removing the entire fuel system is to unscrew the fasteners holding the carburetor mount plate in place.

At this point, you can remove the fuel assembly from the trimmer. The fuel tank, carburetor plate, and carburetor are still connected by the system's fuel lines. Remove them together before disturbing the fuel line arrangement.

It is important to note that before continuing, you should inspect and diagram the fuel line setup to ensure a smoother repair process. Make note of the holes in the fuel tank and choke plate, as well as the connections to the carburetor and primer bulb.

By following these steps, you will be able to successfully remove the trimmer's fuel system, setting the stage for further repairs or maintenance.

Disconnecting the spark plug wire

Once the engine is cool, locate the spark plug wire. This may also be referred to as the spark plug boot. Remove the spark plug cover, and then pull the cap and wire off the spark plug. Check for any corrosion on the top of the contact, and if there is any, clean it with a wire brush. Make sure that the area is free from dirt and debris.

After checking for corrosion, you can then remove the spark plug. Use a combi spanner with a large opening and turn it anticlockwise to do so. Check the spark plug for any damage, such as cracks, or carbon deposits. Also, check the contacts on the electrode. If there are any carbon deposits on the electrode, clean it with a wire brush. If the spark plug is damaged, worn, or you were unable to clean it, you will need to replace it with a new one.

If the spark plug is in good condition and has been successfully cleaned, you can then proceed with replacing the fuel line, performing other maintenance, or storing your string trimmer.

Removing the fuel filter

The fuel filter is located inside the gas tank. It is a white cylinder attached to the end of the small fuel line. To remove the fuel filter, you will need a pair of needle-nosed pliers or a straightened wire clothing hanger with a hook formed on the end.

First, disconnect the spark plug wire by pulling it straight off the spark plug. Then, in a well-ventilated area, remove the fuel cap and empty the fuel tank into an approved storage container.

Now, you can start fishing out the filter. Using your tool of choice, carefully hook the end of the fuel line and pull the fuel filter out of the tank. Once it is out, pull the fuel filter off the end of the fuel line.

Diagramming the fuel lines

Before removing the fuel lines, it is important to understand their configuration. Make a diagram or take a picture of how the fuel lines are connected between the tank and the carburetor. Note the following:

• The hole in the fuel tank where the fuel filter attaches.
• The hole in the choke plate through which the filtered "in" line passes to the carburetor.
• Where the "in" line connects on the carburetor.
• Where the carburetor "out" line passes through the choke plate.
• The primer bulb connection: the "out" line from the carburetor will attach to one end, and the other end will connect to the remaining primer bulb attachment site.
• The correct hole in the fuel tank through which the primer overflow line passes.

Removing the old fuel lines

Trimmer fuel lines are usually tightly attached to their fittings. Attempting to pull them off may break them. Instead, use a flat-head screwdriver to gently push them off.

Remove all the fuel lines from their fittings with a screwdriver. If you are reusing the fuel lines, be careful not to damage them. If you are replacing them, you can cut them flush with the tank and push the remaining bits into the tank.

Finally, tip the trimmer and shake out any remaining fuel line pieces.

Disconnecting the lines from the carburetor

Firstly, it is important to have a clear understanding of the fuel line configuration. Before disconnecting any lines, make a diagram or take a picture of how the fuel lines are arranged between the fuel tank and the carburetor. This will serve as a reference when reconnecting the new fuel lines.

Now, let's begin the process of disconnecting the lines:

• Remove the fuel system cover: This will grant you access to the carburetor. The location of the fuel cover may vary depending on the trimmer model, but it is typically found at the rear of the engine. Remove any fasteners or attachments that secure the cover to the engine.
• Release the throttle cable: Most trimmer throttle cables are threaded through the carburetor choke plate and attached to the carburetor. By simply lifting and tilting the carburetor, you can release the throttle cable.
• Disconnect the lines: Using a pair of needle-nose pliers, carefully remove the fuel lines from the carburetor. It is important to do this gently to avoid any damage to the fittings.
• Deal with the remaining fuel lines: After detaching the lines from the carburetor, you will still have some fuel lines connected to the fuel tank. If possible, pull the lines out of the tank. If they are difficult to remove, you may need to cut them flush with the tank and then use a small screwdriver to push the remaining portions into the tank. Finally, tip the trimmer and shake out any remaining fuel line pieces.

By following these steps, you will have successfully disconnected the fuel lines from the carburetor, allowing you to proceed with the next steps in the fuel line replacement process. Remember to refer to your diagram or picture to ensure a smooth reassembly process.

Reattaching the fuel system

First, double-check your installation of the new fuel lines against your diagram one last time before reassembling the trimmer.

For most trimmers, this means positioning the fuel tank in its place and reinstalling the fasteners that hold the carburetor mount plate in position. Next, reinstall the throttle cable into the carburetor. Thread the throttle cable through its hole in the mount plate and reattach it to the carburetor.

Then, affix the carburetor to the mount plate. This should just require reinstalling some fasteners. Finally, replace the fuel system cover. You may need to guide the carburetor's choke lever through an access opening. Replace all fasteners that hold the cover in position.

Your trimmer is now reassembled with new fuel lines installed.

Frequently asked questions