Whether you call it a weed eater, weed wacker, or string trimmer, your Ryobi is an important tool for a well-manicured yard and garden. You use it to trim around your landscaping, fence posts, water features, and more. When it fails to start, you need to fix it to maintain your home’s exterior appearance.
In this post, we’ll discuss the 13 most common reasons your Ryobi string trimmer won’t start and how to solve them. We’ll cover common issues like a plugged air filter, bad spark plug, dirty carburetor, old fuel, incorrect fuel mix, and more.
Safety Precautions
Before we dive into the reasons why your Ryobi string trimmer won’t start, let’s discuss safety precautions. When working on your string trimmer, it’s important to follow all safety precautions in your operator’s manual to avoid injury.
This guide references 2-cycle and 4-cycle engines. While most Ryobi gas-powered string trimmers on the market today use 2-cycle (2-stage) engines, you will also find 4-cycle (4-stage) engines. Check your operator’s manual if you are unsure what type of engine you are running on your string trimmer.
Reasons Your Ryobi String Trimmer Will Not Start
Plugged Air Filter in a Ryobi String Trimmer
An air filter is used on your Ryobi string trimmer to protect the engine from dirt and other contaminants that can damage it. The air filter should be changed out annually and cleaned regularly.
When the filter becomes dirty and plugged, sufficient air isn’t able to pass through it. The engine doesn’t get the air it needs to start and run. You may think you can resolve this by removing the filter so you don’t run into this plugged air filter problem.
This is a huge mistake. Never operate your string trimmer without an air filter, even if it is just for a short period so you can finish a task. Dirt in the engine can cause wearing and significant engine damage which may result in having to buy a new string trimmer.
Solution: Remove the filter and wipe out any remaining dirt from the air filter housing. Replace a dirty air filter with a new air filter.
Bad Spark Plug in a Ryobi String Trimmer
The spark plug is a maintenance item that should be replaced each year to keep your string trimmer running at its best.
The spark plug will become dirty over time with a buildup of carbon. This can cause the plug to misfire having intermittent starting problems.
Other items to look for is cracked porcelain or burnt electrode; a loose spark plug wire; and an incorrect spark plug gap. These items can also cause a starting issue with your Ryobi.
Solution: You can attempt to clean a dirty spark plug with a wire brush and reuse it. I prefer to replace it. It is an inexpensive part and one of the primary items responsible keep your string trimmer running.
Make sure your spark plug is gapped to the manufacturer’s specification and the spark plug wire (boot) is securely attached.
Plugged Fuel Filter in a Ryobi String Trimmer
The fuel filter can be found inside the fuel tank. It attaches to the fuel line to strain the fuel before it enters the fuel system. Its function is to keep dirt and debris from getting into the fuel system that may clog the lines and carburetor damage your Ryobi trimmer.
When the fuel filter becomes plugged because it isn’t changed out regularly or you are running very dirty fuel, the amount of fuel allowed to pass through the filter is reduced. This can cause your string trimmer to fail to start because the engine isn’t getting the to have starting issues, it may be time to replace the carburetor.
Solution: If the carburetor is dirty, clean it with carburetor cleaner. If it is damaged or worn, replace it.
Old Fuel in a Ryobi String Trimmer
Fuel in your Ryobi string trimmer can go bad and cause starting issues if it is left sitting in the tank for too long. Fuel can also go bad if it is not stabilized before storing your string trimmer for an extended period.
When fuel goes bad, it can become thick and gummy, clogging the carburetor and fuel lines. This can prevent the engine from starting or running.
Solution: Drain the old fuel from the tank and carburetor. Refill with fresh, stabilized fuel.
Dirty carburetor
A dirty carburetor can restrict fuel flow and cause your Ryobi string trimmer to fail to start or run properly. This is a common issue with string trimmers that are not used regularly or when old fuel has been left in the carburetor for too long.
Solution: Remove the carburetor from the engine and clean it thoroughly.
- First, remove the air filter and air filter housing from the engine. This will give you access to the carburetor.
- Use a screwdriver to remove the carburetor from the engine. Be sure to keep track of any gaskets or screws that you remove.
- Take the carburetor apart, being careful to keep track of where all the parts go. Clean each part thoroughly with carburetor cleaner and a soft brush. Pay close attention to the small holes and passages in the carburetor, as these can become clogged with dirt and debris.
- Reassemble the carburetor, making sure that all the parts are in the correct location. Replace any gaskets or screws that were removed.
- Reattach the carburetor to the engine and replace the air filter housing and air filter.
Old Fuel in a Ryobi String Trimmer Gasoline that has been left in your Ryobi string trimmer for an extended period can become stale and create a thick residue that can clog fuel lines, the carburetor, and the spark arrestor. This can make starting the string trimmer difficult or impossible.
Solution: Drain the old fuel and replace it with fresh fuel.
- Turn off the engine and disconnect the spark plug wire.
- Empty the fuel tank into an approved gasoline container.
- Remove the fuel line from the carburetor and drain any remaining fuel into the container.
- Use carburetor cleaner to clean the carburetor and fuel lines.
- Replace the fuel filter, if necessary.
- Fill the fuel tank with fresh gasoline that is mixed to the correct ratio.
- Reconnect the fuel line to the carburetor and reconnect the spark plug wire.
Bad Recoil Starter
Recoil Starter is Bad on a Ryobi String Trimmer The recoil starter on your Ryobi string trimmer is used to start the engine by pulling a rope.
If the starter rope is hard to pull or won’t pull at all, it may be due to a faulty recoil starter.
Solution: Remove the recoil starter assembly from the engine and inspect for damage or wear. Replace if necessary.
Engine is Flooded in a Ryobi String Trimmer
An engine can become flooded when there is too much fuel in the combustion chamber. This can occur when the choke is left on for too long, or when the engine is flooded with fuel due to over-priming or a carburetor issue.
When an engine is flooded, it won’t start because the spark plug is
fouled with excess fuel.
Solution: Remove the spark plug and let the excess fuel evaporate. Dry the spark plug and replace it. Ensure the choke is in the correct position and try starting the engine again. If the issue persists, check for a carburetor or priming issue.
Conclusion In summary, there are several reasons why your Ryobi string trimmer may be hard to start. These include a dirty air filter, a faulty spark plug, a clogged carburetor, old fuel, a bad recoil starter, and a flooded engine. By identifying the specific issue and taking appropriate action, you can get your Ryobi string trimmer back up and running smoothly. Remember to always follow the manufacturer’s instructions and safety precautions when working on your equipment.
