Getting your weed eater started doesn’t seem to be that much of a problem. It’s keeping it running that’s proving to be difficult. Having a weed eater that starts then dies is a definite way to ruin a Sunday morning that you planned to spend tending to the yard. So, if you find yourself having to nurse your weed eater throttle just to keep it running, then there is definitely something going on. Let’s take a look at why this could be happening and what you can do to fix the problem.
Why Does My Weed Eater Start and Then Die? (The Short Answer)
If your weed eater starts and then dies after a short period or when you pull the throttle, then there is probably an issue with either the ingoing air and fuel or the outgoing exhaust. On the ingoing side of the engine, the air filter, fuel filter, or carburetor could be at fault. On the outgoing side, the spark arrestor could be the issue.
Weed Eater Starts then Dies? (4 Possible Causes)
A weed eater that starts and then dies is more common than you would think. I’ve found myself on many occasions standing in the yard tinkering with my weed eater and not getting much yard work done. Fortunately, after some research, I’ve come up with a list of the common causes of this frustrating problem. Let’s take a look.
Clogged Spark Arrestor
As a safety feature on small engines, a screen is attached to the exit of the exhaust pipe called the spark arrestor. This screen is to stop any sparks or flames from being able to exit the exhaust pipe and cause damage to both you and the weed eater.
The one downside to spark arrestors is that they can easily become clogged with exhaust residue. This can include sticky soot and uncombusted two-cycle oil. Even if your engine burns fuel perfectly, the spark arrestor will still clog over time. So, if your weed eater starts and then dies, you will want to inspect the spark arrestor.
First, remove the screws holding the engine cover to the engine. Then, pull the cover from the engine and set it to one side. Next, locate the exhaust pipe and the spark arrestor attached to the exit of the exhaust. Use your screwdriver to remove the mounting screw so the arrestor can be lifted off the exhaust.
Finally, you’ll find the spark arrestor screen sitting between the arrestor plate and the exhaust pipe. For your weed eater to work properly, this screen needs to be clean and free of any build-up and clogging.
Dirty Air Filter
The air filter on a weed eater is very small compared to other garden equipment, such as a lawn mower. This means that they clog up much more quickly. Once an air filter becomes clogged, there will be a reduction of airflow into the carburetor.
This means that when you pull the throttle, the carburetor tries to demand more air but fails. The outcome is your weedeater starts and then dies. So, if this is happening to you, you’ll want to remove the filter and inspect its condition.
For weed eaters like Echo and Craftsman, you can remove the air filter cover without any tools. But if you happen to have an older model from Stihl, you’ll need to grab a special Torx screwdriver. Remove the cover and take a look at the air filter. If it does not appear to be in great shape, then you could have found the reason why your weed eater starts then dies.
Clogged Fuel Filter
Fuel contaminants and debris in the fuel tank are prevented from reaching the carburetor by a small in-tank fuel filter. Due to their size, it doesn’t take much to restrict these small filters and lead to engine problems. So, if your weed eater starts then dies, it could be down to a clogged filter reducing the fuel flow to the carburetor.
To fix this, remove your gas cap and take a look inside the tank. You’ll see the fuel filter attached to a small pipe. Now, you can inspect the filter, but it’s nearly impossible to tell if it’s clogged since the fuel contaminants causing the blockage are so tiny. You would need a microscope to see the offending particles. The only thing you can really see is a discoloration of the filter, unless the filter is covered in grass clippings.
If you give the primer a few squeezes, the engine will create back pressure into the fuel tank. Then, remove the outflow pipe from the tank. The pressure made by squeezing the primer should force fuel out of the removed outflow pipe. If the flow is slow or inconsistent, then the filter could be blocked or at least clogged enough to cause your weed eater to stall.
A Restricted Carburetor
Weed eater carburetors are clever little devices. They use a unique design that enables them to have an internal fuel pump that creates back pressure to the fuel tank and even have the ability to work when they are upside down.
The weak link in these small weed eater carburetors is the fuel diaphragm which is made of a rubber-like material that stiffens over time. As a result, the diaphragm isn’t able to operate efficiently and produce enough pressure back at the tank. This means when you want more power, the carburetor isn’t able to respond.
So, if you remove the diaphragm cover plate from the carburetor, you will be able to remove the diaphragm and check its condition. If you find that it’s damaged or stiff, you’ll need to install a replacement.
My Solutions for a Weed Eater that Starts and Dies Soon After
My weed eater starting then dying is a situation that has led me to address each of the problems described above at some point or another. As a result, over the years, I’ve learned that weed eaters need a lot of TLC if you want to keep them happy. So, here’s how you can address the same problems with your weed eater.
Cleaning or Replacing the Spark Arrestor
While inspecting your weed eater spark arrestor, you had to remove it from the exhaust pipe. What you have to do next is decide if you want to try to clean it or just replace it.
If you happen to have a spare on hand, then I’d just install it and be done. But if you don’t, then you can take a little wire brush and clean it off. There really isn’t much to it other than making sure all the holes in the mesh are clear.
Once you’re happy it’s free of any blockages, install it back on the exhaust pipe, and you’re done. Well, once you finish putting the weed eater back together, that is.
Tools & Parts to Clean or Replace a Spark Arrestor
- Wire Brush
- Replacement Spark Arrestor if Needed
Cleaning or Replacing the Air Filter
If you have discovered your air filter is just clogged up with debris, then you can use an air compressor to clean it out. You might even find that a couple of taps on a hard surface is enough.
However, if it is clogged up with oil, I suggest replacing it with a new air filter. So, remove the filter, clean it, or grab a replacement, and install it into the filter housing. Then, reinstall the filter cover, and you’re done.
Hopefully, you’ll have solved the problem of your trimmer starting and then dying.
Tools & Parts to Clean or Replace an Air Filter
- Air Compressor
- Replacement Air Filter if Needed
Replacing the Fuel Filter
The first thing you want to do is to dump the fuel out of the weed eater. This will make changing the fuel filter easier and less messy. This isn’t a mandatory step, but it does make life much easier.
So, start by removing the fuel cap from the gas tank. If you happen to have a Troy Bilt weed eater with an oversized plastic washer fuel cap retainer, you can just pull it from the tank. For you guys with a Stihl weed eater, I’d leave the fuel cap attached to the little cable. They can be a real pain to reattach.
Once the cap is out of the way, use a hook and fish out the filter in the tank. I don’t have any special tools for this. I just use a piece of wire with the end bent. Now, depending on how much pipe there is attached to the fuel filter, I always cut the filter off, including the pipe attached. This is usually about half an inch of pipe. I do it this way because the fuel filters use a barbed fitting that stretches the fuel pipe.
When I attach a new filter, I like a nice tight fit. But if you think your pipe is too short, maybe cutting the line isn’t a good idea. So, if you don’t want to cut the pipe, just pull the old filter off the pipe, being careful not to pull the pipe from the tank.
Next, push your new filter onto the fuel pipe. Make sure you completely push the filter onto the line so it doesn’t have a chance of falling off. Finally, once you have attached the new filter, drop it back into the fuel tank and reattach the fuel cap.
Tools & Parts to Replace the Fuel Filter
- Replacement Fuel Filter
- Fuel Line Cutters
- Fuel Container
Replacing the Carburetor Diaphragm
My weed wacker starts and then dies, why? Well, there’s possibly a problem with the carburetor’s diaphragm. I know that the word ‘carburetor’ scares a lot of people off as they can be complicated and tricky to work on, but you have choices when it comes to working on the carburetor.
You could order a complete replacement carburetor, a carburetor service kit, or just the diaphragm. So, depending on your confidence with small engines, there’s a repair to fit your skill.
Diaphragm replacement is one of those repairs where you complete most of the repair while making the diagnosis. During the diagnosis, you removed the diaphragm plate and the diaphragm. This means all you need to do is install the new diaphragm and reinstall the plate, and you’re done.
Tools & Parts to Replace a Carburetor Diaphragm
- Replacement Diaphragm
- Screwdriver
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