Generator Only Runs on Choke – [6 Reasons With Solutions]

Generator runs only on choke is not only frustrating but can also lead to costly repairs down the road.

Due to the insufficient quantity of air in the fuel the engine may flood, overheat, or can be severely damaged in the worst cases.

In this guide, we are going to reveal the top 6 reasons why your generator runs only on the choke and how to fix it in an instant without hiring a professional.

Generator Only Runs on Choke

Why My Generator Only Runs on Choke?

1. Bad Quality/Old or Stale Fuel:

Old or Bad quality fuel that sits for more than 3 months without stabilization becomes stale (loses the power of combustibility). Hence when we start the generator with stale fuel the generator’s combustion chamber needs more fuel and less air because of the low combustion power.

Solution: Drain the old/Stale gasoline from the both carburetor and fuel tank and make sure to pour the high-octane or at least a quality fuel with a fuel stabilizer. We also have written a detailed guide about draining the fuel from the carburetor make sure to have a look if you haven’t prior experience.

2. Clogged Main Jet Or Emulsion Tube:

The main jet and emulsion tube ensure better utilization of the fuel by vaporizing it a bit more. If they are clogged due to dirt, debris, or even oxidation, an insufficient quantity of gasoline will be passed and as a result, the combustion chamber receives very less fuel to operate the engine.

Once we ON the choke, enough gasoline rushes to the combustion chamber to start the engine, however with the choke OFF the generator won’t start as there isn’t a sufficient quantity of fuel available for the combustion.

Solution: The main jet and emulsion tube is located inside the carburetor; follow the steps below to clean them in an instant.

  1.  Shut off the fuel valve and drain the fuel from the carburetor’s bowl with the help of a drain screw.
  2. Unscrew the main bolt located at the bottom of the carburetor’s bowl, Remove the bowl and examine the condition of the gasket, as the gasket could be also a culprit for generator runs only on choke.
  3. Remove the main jet located inside the center post/hole.
  4. Apply a few sprays of carb cleaner through the holes of the emulsion tube and main jet. Also, get a copper wire thread/wire bristle and clean the holes of the emulsion tube and main jet more appropriately. Spray some compressed air to remove excessive gunk.
Main jet and Emulsion Tube
Main jet and Emulsion Tube

3. Dirty Pilot Jet:

The pilot jet also allows the gasoline to pass through and mix with the air when the engine is at idle.

If the pilot jet is clogged the amount of gasoline in the combustion chamber will be reduced and as a result, the engine stops working.

Once we ON/Closed the choke the airflow will be reduced and the combustion chamber receives a rich air-to-fuel ratio for powerful combustion (Not Proper combustion).

Solution: The pilot jet is mainly located underneath the idle screw and can be removed with the help of a flathead screwdriver, below are the steps to clean the clogged pilot jet.

  1. Unscrew the race idle/throttle adjustment screw and gently remove the pilot jet.
  2. Clean the holes of the pilot jet with a carb cleaner.
  3. Take a copper wire thread/wire bristle and clean the inside of it. The pilot jet consists of two holes one big hole on the side is for passing the air, however, the small one at the bottom is for mixing the gas with air, both of the holes should be cleaned. Be gentle with the pilot jet as it isn’t made of metal.

PRO TIP: If your generator runs only on a choke do the full cleaning of the carburetor instead of spending hours on each task, spending 30 to 40 minutes to clean and deeply inspect the carburetor worth the effort as it covers all of the solutions I have listed.

4. Fuel Contains Excessive Ethanol:

The fuel with greater ethanol could also be a reason that your generator runs only on the choke.

Though the EPA, ADFC, and other renowned environmental firms encourage using a sufficient amount of ethanol in the fuel to cope with Carbon dioxide emissions, still ethanol is hygroscopic and it should be properly treated otherwise the gasoline and water become separated and as a result, the combustion chamber needs more fuel for proper combustion than usual.

Solution: The presence of water in the gasoline due to the excessive ethanol could not only damage the fuel systems but also the engine, if you suspect that you have poured ethanol-rich fuel make sure to drain it immediately. In addition to that, the system may need to get flushed to prevent further damage.

5. Air Leakages, loosely Mounted Carburetor or Lose Gasket:

A damaged gasket, loosely mounted carburetor or any other air leakages allows the excessive air to mix with the fuel, and as a result, the engine stalls due to the insufficient quantity of gasoline being burned.

Once we cut OFF the airflow by sliding the choke to the ON/Closed position the engine starts running because sufficient gasoline is being transported to the combustion chamber.

Solution: Inspect the gasket, fuel lines, and carburetor connection if you found something loose or cracked, make sure to replace or tighten any loose connection.

NOTE: Though the Damaged gasket or air leakage is a rear problem, still this could happen, I mostly inspect the gasket, lose carburetor, and other air leakages during the cleaning of the carburetor, as I don’t want to specially dismantle the carburetor only for the air leakages.

6. Clogged Fuel lines/Fuel Filter:

With a period of time, the gunk from the fuel tanks of the generator chokes the fuel filter and fuel lines and as a result, the flow of gasoline will be affected.  

Solution: Replace the fuel lines and fuel filter as they aren’t that much expensive. Also to prevent this from happening again, make sure to flush the fuel tank of the gasoline and use fresh and high-quality fuel.

NOTE: If the problem is still there after applying the all methods listed above, make sure to contact a professional generator technician.

Prevent this from Happening Again

  • Use fresh high-quality fuel and add the fuel stabilizer if the fuel will be stayed for more than 3 months.
  • Clean the generator’s carburetor right after 6 months.
  • Use ethanol-free fuel.
  • Stick a piece of duct tape on the gasoline container and write the date on it, if the fuel is too old don’t use it.
  • Keep the fuel valve OFF after operating the machine this will make sure the fuel should be in the bowl to keep safe the jets from being oxidized.

Is It Ok to Run the Generator on Choke?

It depends, running a machine with choke ON/Closed for a few minutes during the freezing temperature isn’t a problem, however running a generator with choke “ON” for a longer time wouldn’t only consumes more fuel and overheat the generators but also damage the gaskets and other important organs of the generator.

Recommended Read: How to run a generator on Choke?

Is It Bad to Run a Generator on Half Choke?

It depends if the engine is warmed the choke should be at the OFF/Run position otherwise the rich fuel-to-air ratio will be transported to the combustion chamber and as a result, the engine may flood or overheat because of the no adequate air in the fuel.

Final Words

If your generator runs only on choke we recommend doing the deep cleaning of the carburetor Instead of spending hours on identifying the core problem.

Also examine the gasket and fuel lines while cleaning the carburetor, if you found them damaged make sure to replace them.

I hope you can now fix your generator runs only on choke without hiring a professional, if I have missed something please comment below, and I will be more than happy to assist you!

Frequently Asked Questions – [FAQs]

Why My Generator Runs Only On Choke?

The main reason your generator runs only on a choke is the combustion chamber needs more fuel due to the old/stall fuel, clogged jets, or excessive air ventilation because of the damaged gasket or any other leakages.

Follow this section of the article to learn more about the cause and how to safely fix the generator that runs only on choke.

Do You Run a Generator With the Choke ON or OFF?

If the engine is cold the generator should start with a choke ON especially if there is a freezing temperature outside, however after warming it up, the choke should be off so that a proper lean air-to-fuel mixture should be fed to the combustion chamber for better efficiency and output.

What Happens if Choke Is Always On?

Excessive heat could build up inside the engine and as a result, the engine may be damaged or provide irregular outputs with poor efficiency, also due to improper combustion because of no air in the fuel the engine could flood as well.

Does a Choke Reduce Air or Fuel?

Choke directly controls the flow of air, however by controlling the air we can also control the quantity of fuel that should be fed to the combustion chamber. 

Is the Choke Connected to the Carburetor?

The choke is either mounted directly on the top of the carburetor or indirectly with the help of cable; in the case of the generators, the chokes are indirectly connected to the generator’s carburetor via cable.



Kashif has been a valuable asset to the electric generator industry for over 5 years. Now, As a skilled energy engineer, he’s been on the front lines of diagnosing problems, fixing broken parts, and performing routine maintenance tasks to keep generators running smoothly.

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