Your chainsaw started like usual, but when you go to remove the choke it begins to sputter and not run unless the choke is left on. It’s important to find the cause and repair it for the best performance.
A Troy-Bilt chainsaw only runs with the choke on when the engine is getting too much air or not enough fuel.
This may be due to old gas, a punctured or clogged fuel line, a plugged fuel filter, clogged fuel vent, a bad carburetor gasket, or a dirty carburetor. The chainsaw may also need a carburetor adjustment.
Before performing repairs on your chainsaw, always remove the spark plug boot for safety. Wait for the engine to cool and for all parts to stop moving. Consult your operator’s manual for additional safety measures.
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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.
7 Reasons a Troy-Bilt Chainsaw Only Runs With the Choke On
1. Old Gas
Old gas is often the reason why a fuel restriction forms in your Troy-Bilt chainsaw.
Reduced fuel to the engine may require you to use the choke to reduce the air getting to the engine. This is to correct the ratio of gas-to-air required for combustion.
Old gas sitting in a Troy-Bilt chainsaw can develop sticky substances and varnish that clogs fuel components and prevents a sufficient flow of fuel to the engine.
When you find old gas in your chainsaw, it’s best to drain the tank and refill it with a fresh gas and oil mixture. Add a fuel stabilizer like Sea Foam to the fuel to assist with cleaning out the fuel system and reducing moisture.
Once you refill the tank with fresh fuel and a stabilizer mix, start and run the chainsaw for several minutes to work the treated fuel through the chainsaw to loosen the sticky substances.
Reduce the negative effects of fuel by following these tips:
- Use gasoline with a minimum 89-octane rating.
- Don’t use gasoline with an ethanol content greater than 10%.
- Mix the gasoline with a premium 2-cycle oil at a ratio of 40:1 for Troy-Bilt 2-cycle chainsaws before adding it to the fuel tank.
- Store fuel in a dry location.
- Consume the fuel within 30 days before it begins to break down or add a fuel stabilizer to make it last a little longer.
To learn more about the right fuel to use, check out this article on choosing and storing gas for a Troy-Bilt chainsaw.
2. Plugged Fuel Filter
A fuel filter’s function is to keep dirt and other contaminants out of the fuel system. You will find the fuel filter for your Troy-Bilt chainsaw inside the fuel tank.
It is a small cylinder-shaped part attached to the fuel line. When the filter isn’t changed regularly, it can become plugged with dirt. This will restrict the amount of fuel that is able to pass through the filter.
When there isn’t enough fuel to mix with air, you may have to run the chainsaw with the choke on to correct the ratio of air mixed with gas so the chainsaw continues to run.
Replace the fuel filter by first taking a clean cloth and wiping around the fuel cap to prevent dirt from falling into the fuel tank. Pull the fuel filter out of the tank. A clean bent wire or needle nose pliers work well for this.
Pull the Troy-Bilt fuel filter out of the line and install a new fuel filter. Place the filter back inside the fuel tank so it sits in the front right position in the tank. Reinstall the fuel tank cap.
3. Punctured or Clogged Fuel Line
The choke may need to be on when the fuel line is clogged preventing a good fuel flow or air is being introduced to the fuel system through a puncture in the fuel line.
When the fuel line is clogged, the clog must be removed. To do this, remove the fuel line from the chainsaw. Spray carburetor cleaner into the line to loosen the clog. Follow by blowing compressed air into the line to remove the clog.
Reinstall the line once the blockage has been removed. If you can’t open up the line or you find the fuel line is dry and cracked, you should replace it with a new one.
Look for a puncture in the line where air can be sucked into the fuel system providing additional air to the cylinder and making the choke necessary to correct the amount of air.
4. Plugged Fuel Vent
There is a small circular vent on a Troy-Bilt chainsaw. This vent is needed to allow air to pass through it so air is allowed to enter the tank when fuel is used and leave the tank when the fuel tank is filled.
When the fuel tank cannot vent properly, the tank will form a vacuum restricting fuel from flowing out of the tank. This will reduce the amount of fuel supplied to the carburetor.
To test whether you have a clogged fuel tank vent, place your saw on a level surface, start it, and remove the choke. If it begins to run sluggishly, remove or loosen the fuel cap to allow air into the tank.
When air is able to pass into the tank, the engine should run fine. Reinstall and tighten the fuel cap while allowing the saw to continue to run to try to replicate the issue where the engine begins to run sluggishly and possibly shut off.
Replace a plugged fuel tank vent. On most Troy-Bilt chainsaws, you will find a small part called a breather installed on the top of the fuel tank just in front of the handle.
5. Bad Carburetor Gasket
A carburetor gasket behind the carburetor can deteriorate, allowing air into the system because the gasket no longer seals correctly.
This causes a Troy-Bilt to run lean when there is more air than fuel in the cylinder than the engine requires. Engaging the choke reduces airflow to compensate for the extra air being pulled in due to the bad gasket.
Access the carburetor and carefully remove the linkages and bolts attached to the carburetor. Remove the carburetor and gasket. Install a new carburetor gasket.
Before you install the carburetor, check it out. You may need to clean it while you have it off the chainsaw.
6. Dirty Carburetor
The carburetor’s function is to regulate the amount of fuel that is mixed with air to form combustion to start and run your Troy-Bilt chainsaw. A buildup of varnish and deposits can make the carburetor unable to correctly perform this function.
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 remove deposits left behind from old fuel.
If the carburetor does not function after being cleaned, you may need to rebuild it or replace it with a new carburetor.
7. Carburetor Needs Adjustment
The carburetor may need to be adjusted to change the RPMs at idle speed and at full throttle. It may be causing the engine to run lean resulting in the need for the choke to be on.
The carburetor may need to be adjusted to change the RPMs at idle speed and at full throttle. There are adjustment screws on the carburetor to make these adjustments.
The screws are labeled “L” for low speed and “H” for high speed. Let the chainsaw idle and adjust the low-speed screw clockwise and counter-clockwise until you find the “sweet spot” where it runs smoothly and not sluggish.
Next, adjust the “H” to get a good smooth RPM at full throttle. Don’t over-adjust and allow the RPMs to increase too much or you will damage the engine.
Troy-Bilt does have some limits to the adjustments you can perform to the carburetor. Your Troy-Bilt chainsaw may require special tools to adjust the carburetor.
If you are having problems with the carburetor, consult your local Troy-Bilt service center.
Still Having Problems with Your Troy-Bilt Chainsaw?
Check out my handy guide Common Troy-Bilt Chainsaw Problems for handy charts listing problems and solutions to many common problems chainsaw owners encounter.
This is a great guide to keep bookmarked. It covers problems with a chainsaw not starting, bogging down, or dying. You can also find information on a chain not turning, the engine only running with the choke on, and more.
In addition, you will find links to more detailed information on each issue.