Weed Eater Won’t Run With Choke Off – 5 Reasons


Man using a weed eater to trim edges of a manicured lawn.

When a weed eater is choked off, it means that its air supply has been cut off. It can also be termed air starvation. There are some reasons why you shouldn’t leave the choke on while using the weed eater.

For starters, it can make the engine splutter instead of accelerating after pushing the throttle trigger. Excessive occurrence of this can cause the engine to stop completely.

Choking off your weed eater is only required when starting the unit and warming it up. After that, the weed eater should run with the choke completely off. If your weed eater only runs at the full or half choke, you have a problem with the unit.

The engine of the weed eater runs on a rich fuel mixture when it is choked. It consumes more fuel, burns fuel inefficiently, gets too hot, and can lead to clogging of exhaust gas passages. Also, if the choke remains on, it can cause thick smoke inside the combustion chamber.

Ultimately, the smoke leaves carbon deposits on the spark plug, which can cause it to misfire easily. This makes the string trimmer engine not start and can affect many other parts of the weed eater and its engine.

What Causes A Weed Eater Not To Run With The Choke Off?

1. Broken Pull Rope

If your weed eater has a broken pull rope, it can make the machine malfunction. Even when you try to repair it, it may not function the same. However, you can buy a new cord for it to function better. The limitation of this is that you will have to play with the choke from full to half, or it will easily die.

2. Blocked Exhaust

Another major cause is a blocked exhaust outlet. The carbon buildup significantly affects the machine and blocks all necessary passages. This is due to a dirty air filter or a bad spark plug.

3. The Wrong Mixture In The Gas/Oil Ratio

If the mixture of gas and oil ratio is not done well, the weed eater can’t easily run on choke-off. Also, if the oil is dirty, this can be disastrous because the motors are really sensitive. Thus, be careful when adding oil to your weed eater.

4. A Dirty Or Clogged Spark Arrestor

A dirty or clogged spark arrestor can also be disastrous and not allow the weed eater to run on choke-off. When you pull the throttle, it increases or decreases the airflow and not the fuel flow. If you want to regulate the fuel flow, you can do it through the venturi effect in the carburetor. When the spark arrestor gets dirty, air doesn’t flow well, so the vacuum effect in the venture of the carb is lessened, causing the fuel to flow less.

5. The Fuel System Is Checking Out And There Is An Air Leak

The weed eater is also tricky at times. While the choke is fully closed, the unit starts and idles slowly. At half-open choke, the unit runs faster but stalls out if you try to use it. At a fully open choke, the unit tends to die out immediately. If there is any kind of air leak, it will cause the engine to slow down or even slow due to the running. However, when the engine starts, it is wiser to choke off the weed eater.

This will provide better service.

In the fuel system, the carburetor could also be causing the problem if there is a blockage in its fuel jets.

Next, the fuel filter might be old or clogged. This causes it to allow less fuel than is required by the weed eater to run smoothly.

When the fuel filter does not allow enough fuel lines through it and into the carburetor. the weed eater requires you to reduce airflow by choking it, to match the amount of fuel that is getting to the combustion chamber.

Lastly, it is possible that the fuel line of your weed eater is worn out. It could be cracked and leaking fuel, or blocked by debris.

How To Fix This?

1. Check For Fresh Fuel

Fuel is vital in the proper functioning of the engine. Thus, if the weed eater refuses to run with the choke off, you can also decide to loosen the gas cap. This may not seem as necessary, but you need to take proper care of the inner parts to ensure everything functions well.

2. Ensure The Engine Is In Good Condition

The engine is vital in the weed eater, and if it isn’t functioning well or the oil is not sufficient, it can easily destroy the machine. Check for any dirt in the carburetor to ensure that it is clean and functions well. Also, be on the lookout for a weak diaphragm and replace any deformed parts.

3. Purchase A New Trimmer Or Clean The Carburetor

If the weed eater is letting you down, you can decide to purchase a new one. However, that should be your last resolution if it can’t be repaired. Also, ensure you clean the carburetor thoroughly to ensure it is not the problem. You can also decide to replace the carburetor or diaphragm gaskets, just check the specifications and look for a compatible one.

4. Screw Out The Exhaust Muffler

You can screw out the exhaust muffler and clean the little screen that is inside it. This will help fix the temperamental weed eaters. Gain access to the ignition and PTO side crank seals and spray them while running. This is because the engine could be sucking in the air and leaning out the fuel-air mixture to the point it will not run unless choked.

5. Unblock the Gas Cap Vent

Check the gas tank cap vent for blockage and clean out the blockage. The gas tank of your weed eater needs to breathe for the smooth flow of fuel.


If you want to set your weed eater well, you need to set the choke to the on position and pull the starter rope not more than six times. If that doesn’t work, set the choke to a halfway position between on and off and pull the starter rope three more times. When the engine starts well, let it run for ten seconds and then turn the choke to the Off or Run position. If it doesn’t start when it is in the halfway position, wait for ten minutes, and repeat the sequence.

Choke on restricts any kind of airflow and chokes the engine.

This causes the air to get through more quickly, and because the carburetor still sprays fuel, it makes the mixture richer and easier to ignite rather than when it is choked off.

Read More

Related Articles

The Best Low-Cost DIY Chicken Coop Ideas

For chicken keepers, raising chickens can be fun and rewarding. However, it can also prove costly. With many chicken coops and hen houses ranging...

The Profitable Guide to Growing Microgreens

Are you looking for a rewarding and profitable venture? Do you have a green thumb and a passion for growing plants? If so, then...