If your weed eater dies when you give it gas, then this is a clue as to what is going on. The fact that your weed eater runs when it’s idling but dies when you increase the throttle means something isn’t meeting your weed eater’s needs. But what could this be? Well, I’ll give you a clue, fuel and airflow. Any ideas? Let’s take a look and see if you are right.
Weed Eater Dies When You Give It Gas (The Short Explanation)
If your weed eater stalls when given throttle, then it’s likely to be down to the fact that the engine cannot get enough gas or there is a restriction in the airflow. Here are four components I would check if my weed eater dies when I give it gas.
- Fuel Filter
- Fuel Lines
- Air Filter
- Exhaust
4 Possible Causes for a Weed Eater That Dies When You Give It Gas
If you haven’t serviced your weed wacker for some time, then it’s likely that a few components either need to be cleaned or need to be replaced. So let’s take a closer look at these components and see how they can cause your weed eater to die when you give it throttle.
Weed Eater Clogged Fuel Filter
One of the first components I would inspect if my weed eater dies when I give it gas would be the fuel filter. This is the small filter that sits inside the gas tank to filter out any impurities and debris in the fuel before it passes through the fuel system to the carburetor and cylinder head.
Even though you may think your fuel filter looks pretty good and there isn’t anything obviously wrong, it likely needs to be replaced. This is especially true if it has been a long time since you last replaced the filter. So, one way to tell if you need to replace your weed whacker’s fuel filter is to do a visual inspection.
Usually, I have a spare fuel filter on hand so that I can make a comparison, but this isn’t essential. For example, an old fuel filter usually looks dark and discolored where it has filtered out the fuel impurities, whereas a new filter looks nice and clean, and the filter material is a light color.
You may look at the filter and think it looks pretty clean but looks can be deceiving. A fuel filter has tiny holes which are measured in microns. So, it doesn’t take much to clog a weed eater fuel filter.
Weed Whacker Clogged Fuel Lines
Next on the list of potential causes why your weed eater dies when you give it gas are the fuel lines. Weed eaters have two fuel lines. One fuel line takes gas to the carburetor, and the second one, known as the primer line, returns air and fuel to the gas tank. Both fuel lines need to be in perfect working order to ensure that the carburetor can prime and push out all of the air in the carburetor and draw in gas.
So, if the intake fuel line is clogged or even damaged, fuel will not be able to make its way to the carburetor. Also, if the return line/primer line is clogged or damaged, the weed eater will not be able to push the air out of the carburetor and fully prime. When this happens, the carburetor will try to ignite a fuel mix with too much air. So, depending on how badly your weed eater lines are clogged or damaged, your weed eater may die when you give it throttle.
So, take a close look at both of the fuel lines and inspect them for damage, such as split lines, crimped lines, and blockages inside the lines. If you find anything that looks out of place, then you’ll need to install new lines.
String Trimmer Clogged Air Filter
Next on the list of potential problems is a clogged or dirty air filter. The air filter installed on your weed whacker filters out any impurities in the air, such as grass clippings and dust. This important job prevents impurities from making their way into the carburetor and the cylinder head.
Also, an air filter is designed to allow a certain amount of airflow into the carburetor to create the necessary air-to-fuel mixture. Therefore, this air-to-fuel mixture ratio is altered as the air filter becomes clogged. However, your weed eater does have a certain amount of tolerance, meaning that it can get dirty and still work. But the filter does have limits.
So, as you pull the throttle on your weed eater, the engine needs air at a faster flow rate. With a new or clean filter, this isn’t a problem. But if your filter is clogged and has a reduced airflow, not enough air will make it to the carburetor, and your engine will likely stall and die.
To inspect your air filter, remove it from your weed eater and check its condition. You will likely find your air filter is covered in debris or oil. You may be able to clean your air filter, or if it is too bad, you may need to replace it.
String Trimmer Clogged Exhaust
Located inside your weed eater’s muffler is a small mesh, also known as a spark arrestor, that prevents sparks from being able to exit and cause potential fires. Now these spark arrestors are nothing new, as they were first used on locomotives in the 1800s to reduce the number of fires trains would start.
Sometime after, during the 1950s, the USDA Forest Service made it mandatory to have spark arrestors installed on chainsaws to prevent forest workers from starting fires on federal lands. So, here we are present day, and you will now find spark arrestors in all your gas-powered equipment, including your weed eater, for the same purpose of preventing unintended fires.
How does this relate to my weed wacker stalling when I give it gas? Exhaust gases have to exit the weed eater’s engine during the exhaust stroke to release engine pressure. If the gases can’t exit the muffler, then the pressure will build in the engine preventing the motor from running. When this happens, the spark arrestor becomes blocked with an oily carbon build-up from the exhaust fumes, progressively reducing airflow through the muffler.
To inspect your spark arrestor, remove it from your weed eater and check how dirty it is. Depending on what tools you have at hand, you may be able to clean the spark arrestor, or you may just want to install a replacement. Typically a replacement spark arrestor should cost less than $15 for a flat mesh design or $20 for a stub style.
How to Fix a Weed Wacker that Stalls When Given Throttle (4 Things to Try)
Now that we have gone over the four common reasons why your weed whacker dies when given gas, let’s take a look at the steps to repair your weed eater. Here are the four fixes you can use to get your weed whacker back up and running and to stop it from stalling when you give it gas.
- Install a Replacement Fuel Filter
- Replace the Fuel Lines
- Swap out the Air Filter
- Install a New Spark Arrestor
Install a Replacement Fuel Filter
To install a new fuel filter on your weed eater, you’ll first need to remove the old filter. So, use a small hook tool and hook out the fuel filter from inside your weed eater’s fuel tank. Now, if you do not have a small hook tool, you can use something like a stiff piece of wire. Just make a bend at the end of the wire so that you can hook the fuel line inside the tank, which is connected to the fuel filter.
Once you have the fuel filter out of the tank, pull the fuel filter free of the fuel line. You don’t need any special tools for this. You can just pull the filter free from the fuel line using your hands. Just be careful not to pull on the fuel line, as you do not want to damage it.
So once you remove the old filter, you can grab your new filter and push it onto the fuel line. Again just be careful with the fuel line connected to the fuel tank. Once you have the new filter installed, you can drop it back into the fuel tank and give your weed eater a try.
Tools & Parts to Replace a Weed Whackers Fuel Filter
- Hook Tool
- Fuel Filter (Weed Whacker Specific)
Replace the Fuel Lines
To complete this repair, you will need to purchase a fuel line repair kit. The kit should include two fuel lines and a fuel filter. Now different weed eaters use different designs of fuel line systems, but in principle, they all work the same. So let’s take a look at the steps.
Steps to Replace Weed Eater Fuel Lines
- Drain the fuel tank.
- Make a note/sketch of which fuel line goes where.
- Remove both fuel lines from the carburetor.
- Remove the fuel tank gas cap.
- Using a pair of hemostat forceps or long needle nose pliers, pull the fuel line from within the gas tank.
- Clean out any debris from within the fuel tank.
- Take one of the new fuel lines and make a 45-degree cut at the end of the line.
- Thread the cut end of the fuel line into the fuel line opening in the gas tank.
- Using either your hemostat forceps or long needle nose pliers, pull the fuel line through the gas tank opening.
- To allow the new fuel line to pass through the tank easier, give the new line a light spray with WD-40.
- Pull the fuel line until about 4-inch of new fuel line is pulled out of the fuel tank opening.
- Cut the 45-degree section from the new fuel line.
- Connect the fuel filter.
- Place the fuel line and fuel filter into the gas tank.
- Connect the fuel line to the carburetor.
- Repeat steps 5-10 for the second fuel line
- Cut the 45-degree section from the new fuel line.
- Place the fuel line into the gas tank.
- Connect the fuel line to the carburetor.
- Refill the gas tank and check for leaks.
Tools & Parts to Replace a Weed Whacker’s Fuel Lines
- Fuel Line Kit
- Hemostat Forceps
- Long Needle Nose Pliers
- Scissors
- WD-40
Swap Out the Air Filter
When it comes to swapping out an air filter, there really isn’t much to it. All you need to do is remove the air filter housing cover, remove the old filter, and install the new filter. Finally, reinstall the filter housing cover, and you are done. Now you might want to wipe the inside of the housing down with a clean rag to remove any oil residue and loose dirt, but other than these few steps, this is all there is to it.
Tools & Parts to Replace a Weed Whacker Air Filter
- Replacement Air Filter (Weed Whacker Specific Air Filter)
- Cleaning Cloth
- Screwdriver
Installing a New Spark Arrestor
As I mentioned before, spark arrestors usually come in two designs, the flat mesh, and the stub design. So, let’s look at the steps for replacing both designs.
Installing a Flat Mesh Spark Arrestor
Depending on the design of your weed eater, you may need to remove the engine cover to gain full access to the muffler. So, remove the engine cover mounting screws and then the engine cover if you need to. Then located on the side of the muffler, you should find a small metal plate held in place with a couple of screws. This is the cover plate for the spark arrestor. So use a screwdriver to remove the cover plate.
Once the plate is removed, you should see the spark arrestor mesh. Typically, the mesh will be resting on the muffler, so it will likely come straight off. Remove the old spark arrestor and position the new one. Next, reinstall the cover plate by placing the cover plate over the spark arrestor and reinstalling the screws.
Finally, if you needed to remove the engine cover, go ahead and install it back onto your weed eater, and you are done. Again this is a pretty quick repair that will make a world of difference.
Tools & Parts To Replace a Mesh Style Spark Arrestor
- Replacement Spark Arrestor (Weed Eater Specific)
- Screwdriver
Installing a Stub Spark Arrestor
A stub-style spark arrestor simply screws in and out of the weed eater’s muffler, kind of like how a spark plug is attached to an engine. So, use a socket wrench to unscrew the old spark arrestor, remove it from the muffler, and then screw in the new one. That’s all there is to it. I would say that this is probably one of the quickest repairs there is when it comes to weed eaters. Two minutes and you are done.
Tools & Parts To Replace a Stub Style Spark Arrestor
- Replacement Spark Arrestor (Weed Eater Specific)
- Socket Set
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