A lawn edger won’t start when it doesn’t get sufficient air, fuel, and spark.
This may be caused by a clogged air filter, plugged spark arrestor, bad fuel, clogged fuel line, plugged fuel filter, bad fuel tank vent, dirty carburetor, bad spark plug, or faulty recoil.
Keep reading as I further explain the effects of old fuel and using the wrong fuel mix in your edger.
Before performing any repairs, remove the spark plug boot. Wait for the engine to cool and the parts to stop moving if you were able to get the edger running previously and now it won’t start.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
13 Reasons Your Lawn Edger Won’t Start (Fix It Now)
If it’s been a while since you performed routine maintenance on your edger including replacing the air filter, fuel filter, and spark plug, start by replacing these maintenance parts.
By replacing these parts, you can ensure these common items are not the reason your edger is not starting.
Plugged Air Filter
The engine requires clean air to start and run. To get clean air, an air filter is used to prevent dirt and debris from entering the air intake. When the filter isn’t changed out regularly, it can become plugged and not allow air to pass through the filter.
It’s best to replace the air filter at least once a year for the average homeowner. Even with replacing it annually, you must check and clean it several times throughout the season.
When you find your air filter is too dirty to continue to use, purchase a replacement if you don’t already have a spare on hand.
While waiting for the replacement filter, DO NOT continue to operate your edger without a filter. Don’t so can cause wearing and damage to the engine.
SOLUTION: Remove the filter and wipe out any remaining dirt from the air filter housing. Be careful not to allow dirt to fall into the intake. Closing the choke before changing the filter will help prevent this. Replace a dirty air filter with a new air filter.
Fouled Spark Plug
The spark plug can become dirty or damaged causing the engine to misfire. Without spark, your edger will not start and continue to run. Remove the spark plug and inspect its condition.
SOLUTION: If you find the spark plug tip is very dark in color, the porcelain is cracked or the electrode is burnt, it’s time to replace it with a new spark plug.
A spark plug that is a little dirty can be cleaned using a wire brush and reused. (I choose to just replace the plug since it’s not very expensive and it affects how well the edger runs).
You will also need to make sure the plug is gapped to the manufacturer’s recommended specification. This information can be found in the operator’s manual. After installing the spark plug, ensure the spark plug wire is securely attached.
Plugged Fuel Filter
The fuel filter can be found inside the fuel tank. It’s a little cylinder-shaped part attached to the fuel line. It is designed to keep dirt and debris out of the fuel system.
This filter can become plugged when it isn’t changed regularly or you are running very dirty fuel. This can restrict fuel flow to the engine causing the edger to fail to start.
SOLUTION: Wipe around the fuel tank cap so dirt doesn’t fall into the tank. Remove the cap. Locate the fuel filter in the fuel tank. Hook the fuel line with a clean bent wire and pull the filter out of the tank.
Securely hold the fuel line and remove the filter from the line. Attach the new fuel filter and place it back inside the fuel tank.
Note: Some models have a ring clip to hold the line to the fuel filter. Be careful not to lose the clip when replacing the filter.
Incorrect 2-Cycle Oil Mix
Using straight gas in a 2-cycle edger will damage the engine and cause it to seize up. Adding straight gas is a quick way to ruin your edger.
The 2-cycle engine in an edger uses gas and oil mixed at a ratio of 50:1, 40:1 or 32:1. For example, 50:1 mix equals 50 parts gasoline to 1 part oil.
You can find the correct mix ratio for your model in your operator’s manual. You may also find it on the original fuel cap. The ratio varies by manufacturer and age of the units. Below I list the gas-to-oil mix for some current 2-cycle edgers.
| Manufacture | 2-Cycle Gas to Oil Mix Ratio |
|---|---|
| ECHO | 50:1 |
| Husqvarna | 50:1 |
| MTD | 40:1 |
| Poulan Pro | 40:1 |
| RedMax | 50:1 |
| Ryobi | 50:1 |
| Shindaiwa | 50:1 |
| Stihl | 50:1 |
| Tanaka | 50:1 |
| Toro | 50:1 |
| Weed Eater | 40:1 |
| Troy-Bilt | 40:1 |
| Yard-Man | 40:1 |
When creating this mix, use unleaded gasoline with a minimum octane rating of 89 (mid-grade) and maximum ethanol content of 10%. Add a 2-cycle premium oil that is ISO-L-EGD and JASO M345 FD certified.
Mix it in an approved gas can before adding it to your edger. I like this 2-cycle mix by Kawasaki. It comes in a 6.4 oz bottle that can be mixed with 2.5 gallons of gas for a 50:1 ratio or mixed with 2 gallons of gas for a 40:1 ratio.
| Mixture | 1 Gallon | 2 Gallon | 2.5 Gallon |
|---|---|---|---|
| 50:1 | 2.6 oz | 5.2 oz | 6.4 oz |
| 40:1 | 3.2 oz | 6.4 oz | 8.0 oz |
| 32.1 | 4.0 oz | 8.0 oz | 10.0 oz |
Solution: Drain the fuel tank and fill it with the correct gas to oil mix. If you continue to have problems, have a small engine mechanic diagnose the problem and determine whether a cost-effective repair can be made.
2-Cycle Premixed Fuel
A great option to reduce fuel problems and extend engine life is using an ethanol-free fuel mix. Many manufacturers offer their own brand of premixed fuels.
This is an ethanol-free blend of oil and fuel that is ready to pour into your edger’s fuel tank.
You won’t have to deal with the bad effects of ethanol as discussed in the fuel section. Also, it’s convenient to have fuel available on your shelf when you need it.
Incorrect or Insufficient Engine Oil in a 4-Cycle Engine
4-cycle engines have separate fill ports for the engine oil and the fuel. DO NOT mix the oil and fuel together if you own this type of engine. Never use 2-cycle oil in a 4-cycle edger.
*STIHL’s 4-MIX engine is an exception to this. These engines are designed to use a gas and oil fuel mix.
Oil is required to keep the engine components lubricated. When the wrong type or not enough oil is used, friction can build in the engine and overheat causing your edger not to start and possibly ruin the engine.
Solution: Drain the engine oil and fill it with the correct oil grade. When running your edger in very cold or very hot temperatures, you may have to adjust the viscosity to your ambient temperature.
If you continue to have problems, have a small engine mechanic diagnose the problem and determine whether a cost-effective repair can be made.
Old Fuel
Old fuel left in an edger won’t only cause fuel restrictions, but it can also damage the carburetor and engine. Gasoline can begin to break down as quickly as 30 days after purchase.
The ethanol found in most types of gasoline attracts moisture from the air. This moisture and ethanol mixture gums up the fuel system and components.
Because gasoline can begin to break down and become less effective as soon as 30 days after purchase, the fuel must be consumed within this time frame.
If you are unable to use it in this amount of time, add a fuel additive to stabilize the fuel so it lasts a little longer.
Always use unleaded gasoline with a minimum octane rating of 89 (mid-grade) and maximum ethanol content of 10% (E10). Never use E15 or E85 in the engine as this will damage the engine and most likely void manufacturer warranties.
Solution: Drain any old fuel remaining in your edger and fill it with fresh fuel. This is an oil and fuel mix for a 2-cycle engine and unleaded gasoline for a 4-cycle engine.
Add a fuel stabilizer like Sea Foam Motor Treatment to stabilize the fuel, clean the fuel system and reduce moisture in the fuel.
Bad Primer Bulb
A cracked primer bulb that won’t fill up with fuel won’t function correctly to get fuel to the carburetor for starting the edger.
Solution: Replace with a new primer bulb.
Fuel Line Blocked
Old fuel can leave a gummy sticky deposit behind that restricts fuel flow. This can clog the fuel line and restrict the fuel flow your edger requires to start.
Solution: Replace a fuel line in the edger when it is cracked, kinked, or clogged.
Plugged Fuel Tank Vent
The fuel tank vent allows air into the tank. Without a vent, the fuel tank will create a vacuum that won’t allow fuel to flow through the edger.
A good indication you may have a fuel tank vent problem is when the edger runs for a few minutes and then shuts down and won’t start until you remove the fuel cap to allow air into the fuel tank.
To further confirm a vent problem, replace the cap and run the edger to replicate the problem where the edger dies and won’t start.
Solution: Replace the fuel tank vent so the air can flow into the fuel tank. The fuel tank vent may be attached to the fuel line coming out of the fuel tank or it may be a check valve in the fuel cap. It varies by manufacturer.
Clogged & Dirty Carburetor
The carburetor regulates the amount of fuel that is mixed with air to create combustion in the cylinder. Old fuel will gum up and clog the carburetor so it no longer functions properly.
Solution: If you are a little mechanical you should be able to handle cleaning your carburetor. Clean the carburetor by taking it apart and using carburetor cleaner to clean it.
If the carburetor does not function after being cleaned, you may need to rebuild it or replace it with a new carburetor. Carburetors for an edger can run between $60-$140 depending on the manufacturer.
Depending on the model edger you run, the age of the edger, and the price of the carburetor, it may be best to invest in a new edger rather than put money towards replacing a carburetor on an old edger.
Bad Recoil Starter
The edger uses a recoil to start the engine. A bad pulley; loose or missing spring; or broken clips can keep your recoil from working.
Solution: You can attempt to replace the spring and restring the recoil. If it does not work because other components in your recoil are damaged, such as the clips or the pulley, you are better off just replacing the recoil assembly.
Bad Spark Arrestor
You will find a spark arrestor in your edger that can prevent it from starting. The spark arrestor is a small screen that can get plugged with soot.
Solution: Disconnect the spark plug boot. Remove the spark arrestor and clean it with a wire brush to remove the soot. If you are unable to clean it sufficiently or it is broken or has a hole in it, replace it with a new spark arrestor.
Engine is Flooded
The engine can become flooded when the choke is in the closed position and the starter rope was pulled many times allowing too much gas into the carburetor.
It can also happen with the switch off and the starter rope being pulled multiple times or when the primer bulb is pushed too many times.
Solution: Use the following procedure to “unflood” your edger so the engine gets the correct fuel-to-air ratio required to start and run.
How to Fix a Flooded Engine on an Edger
- Turn the switch on to the run position.
- Move the choke lever to the run position.
- Press the throttle trigger while pulling the starter rope over and over. This can take anywhere between 5 and 15 pulls before it starts. The edger’s engine will sputter first. Continue to pull a few more times and it should start.