Everyone loves the smell of freshly cut grass on a cool spring day or the look of a perfectly manicured lawn. With hours upon hours of work spent maintaining your yard each year, you rely on your favorite tools to make it happen. What would happen, however, if you couldn’t start your string trimmer?
String trimmers often are hard to pull start because of a broken part within the recoil mechanism or because the engine is misfiring when trying to start. Often, replacing the broken part or clearing the cause of an engine misfire will solve the issue.
While there is no single reason that a string trimmer is hard to start, diagnosing the issue and correcting it is relatively simple and will save you time, labor, and money. Read on to learn what these problems could be and how you can fix them!
How a String Trimmer’s Starting Mechanism Works
In order to identify why the string trimmer is hard to pull when starting, it is important to understand how the starting process works. Gas string trimmers a small combustion engine in order to power the mechanism actually cutting your weeds.
This means, similar to a car, your engine is powered by a small series of fires that use gasoline as fuel to move the pistons (source).
To make this process of combustion begin, you must pull the start cord on your trimmer to fire up the engine. When you pull this start cord, you are actually using a series of magnets to convert your kinetic energy, the energy of your motion, into electricity.
This electricity is diverted to the spark plug (source).
At the same time, your motion of pulling the start cord is attached to a gear-like mechanism, so that each time you pull the cord, the gear actually engages to open a small chamber that fills with fuel and then closes again.
When this chamber closes, full of fuel, the spark plug then releases the electricity into the fuel. This, quite literally, “sparks” the fuel and sets it on fire.
When this fire occurs, the pressure within the chamber changes, making the entry hole to the chamber open again. When it opens, the leftover gases in the chamber are released from the engine via the exhaust pipe, and new fuel enters the chamber for the process to start again.
Eventually, this occurs enough times so that the motion of this chamber opening and closing generates the energy it needs to spark the chamber itself, thus no longer relying on your pull.
This incredibly complex system is what creates the energy that powers your string trimmer. Thus, if one little issue occurs along the way, it can explain why your pull cord is not working.
Why Your String Trimmer Is Hard To Pull and How To Fix It
Now that we understand how the string trimmer works, we can look at why it might be incredibly hard to pull. Most of the time, the cause is an issue within the pull mechanism itself.
The three most common issues associated with a string trimmer pull mechanism that makes it harder to pull are a broken cord, a stuck cord, or a recoil spring that is damaged.
Another issue that could make it so your string trimmer is hard to pull could be related to the quality of fuel in your machine or an issue with the exhaust system. Here is a quick explanation of each of these issues, as well as how to fix them.
A Broken Pull Cord
After a lot of use, sometimes, pull cords just break. While most of the time when they break the cord comes out of the system entirely, sometimes, it will get tangled up within the pull mechanism, making it all but impossible to pull.
To fix this issue, all you need to do is take out the coil, unthread the broken cord, and rethread a new one. New cords can be ordered online, and rethreading the coil is incredibly simple.
A Stuck Cord
A stuck cord is often stuck for the same reason a broken cord can cause you issues, it is tangled up or has something lodged within the pull mechanism. From the number of weeds you are trimming daily, it is a real possibility that there is simply a build-up, making the coil stuck.
To fix this, simply remove the coil mechanism, unwind the cord, and coil it. Be sure to take out any weeds or other build-up that may impair you from starting it.
A Damaged Recoil Spring
The reason that a pull cord recoils into a nice clean circle within the pull mechanism is that there is a spring that forces the mechanism to retract. Though this offers some resistance, the amount of resistance it provides is relatively small.
If you have an issue in pulling the cord, then the recoil spring is probably damaged or broken. Simply remove and replace the recoil spring and this will fix your issue!
Bad Fuel Or Exhaust Buildup
Though an issue with your pull mechanism is the most common reason that your pull start is not working, there is also a chance that an exhaust buildup or bad fuel is to blame.
When you pull the cord, you are essentially doing the manual work of creating combustion within the engine. This involves, as you know, a lot of moving parts. If you have fuel that is just poor quality and will not ignite or if you have an exhaust build-up, your engine will not start.
This failure for the engine to start will also make it so that you cannot pull the start cord.
The design of the combustion engine is meant to be safe, so if you have an exhaust buildup or fuel that is not igniting, the machine will, by its design, resist the movement of the pistons that open and close the combustion chamber.
Since these pistons are also attached to the pull cord, it will add resistance to the cord, making it so it is harder to pull. To fix this issue, simply clean out your exhaust system and make sure you are using better quality fuel that will ignite.
When it comes to your pull start string trimmer, a number of issues could explain why it is not starting. Each of these issues are rather easy to resolve, but it is important to take the time to assess which issue could be impairing your pull string from working and taking the appropriate steps to fix it.