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12 Reasons a Homelite String Trimmer Won’t Start (SOLVED)

It can get frustrating when you continue to pull on the starter cord and the engine won’t start. When this happens, you need to look for items that can prevent air, fuel and spark required for combustion.

A Homelite string trimmer won’t start due to a plugged air filter, bad spark plug, wrong fuel mixture, plugged fuel filter, dirty carburetor, bad fuel cap, faulty recoil, plugged spark arrestor, or a flooded engine.

Keep reading for additional items that can contribute to your starting problem. Always remove the spark plug wire prior to performing any repairs or maintenance on your Homelite.

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Follow all safety instructions provided in your equipment operator’s manual prior to 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.

Start with Checking & Replacing Your Homelite Maintenance Parts

When you find your Homelite string trimmer won’t start, the best thing to do is to first rule out the air filter, fuel filter, and spark plug as being part of the problem. The are routine maintenance items that should be replaced annually at minimum.

12 Reasons For Your Homelite String Trimmer Starting Problem

1. Plugged Air Filter Will Cause a Homelite String Trimmer to Not Start

The air filter is essential to keeping dirt out of the engine and damaging it. When the air filter isn’t cleaned or replaced regularly, it can become so plugged that enough air isn’t able to pass through it.

This can cause the engine to fail to start. I recommend starting each year out with a new Homelite air filter. Then check and clean it after every 5 hours of operation to make sure it is still in good condition.

If you find the filter is damaged, you must replace it. If it’s just a little dirty, remove the filter and clean it.

NEVER run your Homelite string trimmer with a very dirty air filter or without an air filter. It can be tempting to try to finish your trimming task by removing a plugged filter and running the trimmer while you wait on a new filter replacement.

Even a small amount of dirt can damage the engine.

SOLUTION: Remove the filter and clean it using the procedure below. If you find it is damaged, brittle, or has a tear in it, purchase and install a new filter.

Clean a Homelite string trimmer FOAM air filter:

  • Remove the air filter cover and the air filter.
  • Wipe out any loose dirt remaining in the filter housing and cover.
  • Clean the foam filter with warm water and mild detergent.
  • Rinse the filter until the water runs clear.
  • Squeeze excess water out of the filter. Don’t wring it out as you may tear the filter.
  • Allow the filter to air dry.
  • Lightly cover the foam filter with clean engine oil. Squeeze excess oil from the filter. You don’t want it dripping with oil.

2. Bad Spark Plug Will Cause an Homelite String Trimmer Not to Start

The spark plug is another maintenance item that should be replaced once a year to keep your Homelite string trimmer running at its best.

Over time, the spark plug can become dirty, the porcelain can break, or the electrodes can wear causing the plug to misfire or not work. This can cause your starting problem.

A loose spark plug wire or incorrectly gapped spark plug can also contribute to a starting problem.

SOLUTION: Before removing the spark plug form your Homelite string trimmer, wipe around the plug to remove all dirt and debris. Remove the plug and check its condition.

Replace a spark plug that is very dark in color, has signs of wearing or is damaged.

You can attempt to clean a mildly 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 for keeping your Homelite string trimmer running.

Make sure your spark plug is gapped to the manufacturer’s specification, install the spark plug and securely attach the spark plug wire (boot).

3. Plugged Fuel Filter Will Cause a Homelite String Trimmer Not to Start

The fuel filter used on a Homelite string trimmer can be found in the fuel tank. This filter is used to strain fuel before it enters the fuel line. It is designed to keep dirt and debris out of the fuel system.

Just like the air filter, the fuel filter can become plugged when it isn’t changed out regularly. I recommend replacing the fuel filter at least once a year while checking it periodically.

If you find the fuel is dirty, you may need to drain the fuel tank, fill it with fresh fuel and replace the fuel filter.

When the fuel filter becomes clogged with dirt, it will restrict the amount of fuel that is able to flow through the filter and into the fuel lines. This can keep your Homelite engine from getting the fuel it requires to start and run.

SOLUTION: Locate the fuel filter inside the fuel tank and replace the plugged filter. Replace the fuel if you find it dirty as well.

  • Wipe around the fuel cap to remove any loose dirt so it doesn’t fall into the fuel tank once you remove the cap.
  • Gain access to the filter. A clean bent wire works well to “fish” the filter and pull it out of the tank.
  • Remove the old filter from the fuel line.
  • Install the new fuel filter.
  • Place the filter back inside the fuel tank and reinstall the fuel cap.

4. Incorrect 2-Cycle Oil Mix in a Homelite String Trimmer Will Causing Starting Problems

Adding straight gas to a Homelite string trimmer is a sure way to ruin the trimmer. Gas runs extremely dry and won’t provide the lubrication required to run a 2-cycle engine.

Make sure you are using a gas-and-oil mixture when adding fuel to the tank.

Read more information in Gas and Oil Fuel Mix Homelite String Trimmers Use.

Homelite 2-Cycle Gas to Oil Mix

A 2-cycle Homelite string trimmer requires a gas-to-oil ratio of 50:1. 50 parts gas needs to be mixed with 1 part oil.

Mixture1 Gallon Gas2 Gallon Gas2.5 Gallon Gas
50:12.6 oz Oil5.2 oz Oil6.4 oz Oil
Homelite 2-Cycle String Trimmer Gas to Oil Mix

When creating the oil and gas mixture, use unleaded gasoline with a minimum 87-octane rating and a maximum 10% ethanol content. Add a 2-cycle premium oil that is ISO-L-EGD and JASO M345 FD certified.

Mix the fuel and oil in an approved gas can before adding it to your string trimmer. Homelite recommends using a 2-cycle oil like Ethanol Shield. Kawasaki 2-cycle oil is also a good alternative.

2-Cycle Homelite Premixed Fuel

A great option to reduce fuel problems and extend engine life is using an ethanol-free fuel mix. This is an ethanol-free blend of oil and fuel that is ready to pour into your string trimmer’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. TruFuel is a good 50:1 premixed fuel option.

SOLUTION: Drain the fuel tank and fill it with the correct gas to oil mix. If you continue to have problems after adding the wrong fuel, have a small engine mechanic diagnose the problem and determine whether a cost-effective repair can be made.

Old Fuel in a Homelite String Trimmer Will Cause Starting Problems

Old fuel left in a Homelite string trimmer won’t only cause fuel restrictions, but it can also damage the carburetor and engine.

Because ethanol is found in most types of gasoline and gas begins to break down as soon as 30 days after purchase, it’s important to use fresh gasoline with low ethanol content.

Ethanol is not kind to the small engine used on your Homelite trimmer. This product naturally attracts moisture from the air causing premature corrosion and fuel restrictions.

The ethanol and water mixture not only leaves behind varnish and gummy deposits, but it can also separate from gas over time causing potential engine damage.

Because of this, always use unleaded gasoline with a minimum octane rating of 87 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.

I know it’s hard to know how quickly you’re going to go through fuel. It’s like trying to anticipate how much rain and sunshine you’ll see that will impact how quickly the grass grows.

To keep your fuel system clean and to reduce the negative effects of ethanol, add a fuel stabilizer.

I like Sea Foam Motor Treatment as a fuel stabilizer. Some 2-cycle oils include a fuel stabilizer, but you’ll need to read the details on the oil bottle to determine how long the product will stabilize the fuel.

SOLUTION: Drain any old fuel remaining in your string trimmer and fill it with fresh fuel. This is an oil and fuel mixture for the 2-cycle engine on your Homelite trimmer.

6. Bad Primer Bulb in a Homelite String Trimmer

A cracked Homelite primer bulb that won’t fill up with fuel won’t function correctly to get fuel to the carburetor for starting the string trimmer.

If the primer bulb appears in good condition and it still won’t fill, check for a clogged fuel filter or fuel line.

SOLUTION: Check the condition of the primer bulb. Ensure the fuel line is attached securely and not leaking. Replace with a new primer bulb when you find any wear.

7. Clogged Fuel Line in a Homelite String Trimmer

Old fuel sitting in your string trimmer can leave a gummy sticky deposit behind that restricts fuel flow. This can clog the fuel line and restrict the fuel flow your string trimmer requires to start.

SOLUTION: Replace a fuel line on your Homelite string trimmer when it is cracked, kinked, or clogged.

8. Plugged Fuel Tank Cap in a Homelite String Trimmer

The fuel tank vent allows air to pass into the tank. Without a vent, the fuel tank will create a vacuum that will prevent fuel from leaving the fuel tank and getting to the carburetor.

A good indication you may have a fuel tank vent problem is when your Homelite trimmer runs for a few minutes and then shuts down and won’t start until you remove or loosen the fuel cap to allow air into the fuel tank.

When you tighten the cap and allow it to run and the string trimmer dies and fails to start until the cap is loosened, you most likely have a fuel vent problem.

SOLUTION: The vent for the fuel cap is located in the Homelite fuel cap. Replace a bad fuel cap.

9. Dirty Carburetor on a Homelite String Trimmer

The carburetor regulates the amount of fuel that is mixed with air to create a combustion in the cylinder. Old fuel will gum and clog the carburetor so it no longer functions properly.

This is a common problem with carburetors and old gas.

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.

Depending on the model and age of the string trimmer you use, the price of a carburetor, and the cost of labor, it may be best to invest in a new string trimmer rather than put money towards replacing a carburetor on an old trimmer.

10. Bad Recoil Starter on a Homelite String Trimmer

A bad pulley; loose or missing spring; or broken clips can keep the starter recoil from working. This will prevent starter from catching the crankshaft to start your Homelite string trimmer.

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.

11. Plugged Spark Arrestor in a Homelite String Trimmer

You will find a spark arrestor in your Homelite string trimmer that can prevent it from starting. The spark arrestor is a small screen installed on the muffler to prevent hot materials from discharging causing burns or a potential fire.

Homelite recommends cleaning the spark arrestor every 50 hours to keep the screen free of soot so it doesn’t become plugged causing a running or starting problem.

SOLUTION: Remove the spark plug boot and allow the engine to cool before cleaning the spark arrestor.

Remove the spark arrestor screen from the muffler. Clean the screen using a small wire brush to remove carbon deposits.

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 screen.

12. Flooded Homelite String Trimmer

You may have flooded the engine by pulling the starting rope too many times with the choke closed. It may also flood when the primer bulb is pushed too many times.

Both of these procedures will introduce too much gas into the carburetor and the engine won’t start. Don’t worry, this is not a serious problem and can be corrected.

SOLUTION: Use the following procedure to “unflood” your Homelite string trimmer so the engine gets the correct fuel-to-air ratio required to start and run.

How to Fix a Flooded Engine on a Homelite String Trimmer

  • Move the choke lever to the START 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. Your Homelite string trimmer will sputter first. Continue to pull 2 to 3 more times and it should start.