Intro
Hey, welcome back to Backyard Engine Pro. String trimmers are one of those tools that get used hard all season and then tossed in the corner of the garage when the weather turns. A few minutes of proper storage prep makes the difference between a trimmer that fires right up next season and one that needs a carburetor cleaning before you can use it again.
The good news? Storing a string trimmer correctly only takes about 15 minutes. Let’s walk through it.
Quick Overview
- Clean the trimmer
- Handle the fuel
- Check key components
- Store in a dry location in the right position
Why Proper Storage Matters
String trimmers are particularly vulnerable to storage-related problems because they run on a two-stroke fuel mix that degrades faster than straight gasoline. The tiny carburetor passages on a two-stroke engine are also more susceptible to varnish clogging than larger four-stroke carbs. A trimmer stored improperly for a winter comes out in spring with a clogged carburetor, degraded fuel lines, and a fouled spark plug almost every time.
A trimmer stored properly comes out ready to start on the second pull. The prep work is genuinely worth it.
Step 1: Clean the Trimmer
Before you address fuel or mechanical components, get the trimmer clean. Grass, sap, dirt, and debris left on the trimmer during storage trap moisture against surfaces and accelerate corrosion and deterioration.
What to do:
- Remove the trimmer head and clean away any grass clippings, string residue, and debris packed around the head and shaft. The area around the cutting head accumulates the most buildup and is the most prone to corrosion if left dirty
- Wipe down the engine housing, air filter cover, and shaft with a clean dry cloth
- Clear any debris from around the engine cooling vents and air intake areas
- Inspect the trimmer head for any damage, worn bumper, or depleted string. If it needs a restring or the head is worn, now is a great time to address it so the trimmer is truly ready to go in spring
- Let everything dry completely before moving to fuel handling
Step 2: Handle the Fuel
This is the most critical storage step for a string trimmer, even more so than for a four-stroke mower. Two-stroke mixed fuel degrades faster than straight gasoline, and a trimmer carburetor left with old mixed fuel over winter is almost guaranteed to have varnish-clogged passages by spring.
Option 1: Add Fuel Stabilizer
If you want to keep fuel in the system during storage, treat it before it has a chance to degrade.
- Add a quality fuel stabilizer to the tank at the dose recommended on the label
- Run the engine for 5 to 10 minutes after adding the stabilizer to circulate treated fuel through the carburetor and fuel lines. This is the step most people skip and the reason stabilizer doesn’t always work as expected. The carb needs treated fuel running through it, not just fuel sitting in the tank
- Let the engine cool, then store
Option 2: Drain the Fuel Completely
For a two-stroke trimmer going into winter storage of more than a few weeks, draining the fuel entirely is the most reliable protection.
- Pour any remaining mixed fuel out of the tank into a fuel-safe container. Old mixed fuel should not be reused after sitting for an extended period
- Run the engine until it dies from fuel starvation to empty the carburetor and fuel lines completely
- A dry carburetor cannot develop varnish deposits during storage and is the cleanest possible state to store a trimmer in
For two-stroke equipment specifically, draining is generally the preferred method since mixed fuel degrades so quickly. If the trimmer will sit for more than 30 days, drain it.
Step 3: Inspect the Air Filter
With the trimmer clean and the fuel handled, take a few minutes to check the air filter. A clean filter means easier starting next season and gives you a head start on the spring startup routine.
What to do:
- Remove the air filter and inspect it closely
- Tap foam or felt filters gently to dislodge loose debris, then wash foam filters with warm soapy water, rinse thoroughly, and let dry completely before reinstalling
- Replace the filter if it’s torn, heavily soiled, or deteriorating. Going into storage with a compromised air filter means dealing with it in spring when you’re ready to start mowing, not when you have time to deal with it calmly
Step 4: Check the Spark Plug
Storage time is a natural opportunity to assess the spark plug and either clean it up for spring or replace it now so it’s not something you have to deal with later.
What to do:
- Remove the spark plug and inspect the electrode carefully
- Clean light carbon deposits with a wire brush
- Check the gap and adjust if needed. Most two-stroke trimmer engines call for a gap between 0.025 and 0.030 inches, but verify with your manual
- Replace the plug if there’s heavy fouling, corrosion, a cracked insulator, or a worn electrode
- Some owners prefer to coat the inside of the cylinder with a small amount of two-stroke oil through the plug hole before long-term storage to prevent corrosion on the cylinder walls. Remove the plug, add a few drops of clean two-stroke oil, pull the cord several times to distribute the oil, then reinstall the plug
Step 5: Inspect the Fuel Lines
String trimmer fuel lines are made of rubber that’s particularly susceptible to ethanol degradation and heat exposure. Storage time is the right moment to inspect them carefully and replace anything that’s showing its age before it becomes a problem.
What to do:
- Inspect both fuel lines (supply and return) carefully along their full length for cracks, hardening, or any sections that look collapsed or deformed
- Gently bend each line and feel for brittleness or resistance that indicates the rubber has lost its flexibility
- Replace any line that shows visible cracking, hardening, or that won’t flex easily. Fuel line is inexpensive and replacing it during storage is much easier than diagnosing a fuel delivery problem next spring when the line finally fails completely
- Check the fuel filter inside the tank at the same time. If it looks dark or deteriorated, replace it
Step 6: Store in a Dry Location
Where you store the trimmer matters as much as how you prepared it. Moisture is the enemy of everything mechanical, and a trimmer stored in a damp environment will undo much of the prep work you just did.
What to do:
- Store indoors whenever possible. A garage or shed that stays reasonably dry through the winter is ideal
- Avoid storing directly on a concrete floor. Concrete draws and transfers moisture, and leaving the trimmer on bare concrete accelerates corrosion on metal surfaces
- Hang the trimmer on a wall hook or store it on a shelf above floor level to keep it away from floor moisture and potential flooding
- Keep the trimmer away from areas of the garage where temperature extremes are likely since repeated freeze-thaw cycles are hard on rubber components
Step 7: Store in the Proper Position
How the trimmer sits during storage affects both the fuel system and the physical condition of the machine.
What to do:
- Store the trimmer vertically hanging from a wall hook when possible. This is the most space-efficient option and keeps the shaft straight without any pressure or stress on it
- If storing horizontally, lay the trimmer flat on a shelf with the engine end supported to avoid putting pressure on the middle of the shaft. A bent shaft causes vibration problems and can’t be straightened reliably
- Never lean the trimmer against a wall at a sharp angle with weight on the shaft since even a moderate bend can develop over a long storage period
- Make sure the trimmer head is not in contact with anything that could compress or deform it during storage
Common Mistakes to Avoid
- Leaving old mixed fuel in the tank for the entire winter without treatment. Two-stroke mixed fuel degrades faster than straight gasoline and virtually guarantees a clogged carburetor by spring
- Storing in a damp basement or directly on a concrete floor where moisture contact accelerates corrosion
- Skipping the cleaning step and letting packed grass and sap sit against metal surfaces for months
- Storing with the shaft bent or under pressure, which can cause a permanent bend that creates vibration problems when you use it again
Pro Tip
For winter storage specifically, draining the fuel is almost always the better choice over stabilizing for a two-stroke trimmer. Mixed fuel degrades faster than straight gas, and even stabilized mixed fuel left in a trimmer carburetor for six months has a higher chance of causing varnish problems than a trimmer stored completely dry. Drain it, run it dry, and start fresh with properly mixed fresh fuel next spring.
Final Thoughts
Storing your string trimmer the right way is a 15-minute job that prevents the kind of spring startup problems that turn into 45-minute carburetor cleaning sessions. Clean it, handle the fuel properly, check the key components, and put it away in a dry spot in the right position.
Now go get that trimmer put away right. You’ve got this.