How to Fix Briggs & Stratton Float Carburetor

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Things You'll Need

  • Screwdriver

  • Adjustable wrench

  • Carburetor cleaner

  • Steel wool

  • Towel

  • Spray lubricant

  • Two gaskets

Failure of carburetor gaskets allows gas to leak out of your lawnmower.

Briggs & Stratton manufactures small engines for lawnmowers and landscaping equipment. Fuel flows into a bowl in a float carburetor. The float rises as the fuel level fills the bowl and lowers as the gasoline is used by the engine and allows more flow into the bowl. The gaskets on the top and bottom of the float may deteriorate due to age and allow gas to drip from the carburetor bottom. A faulty needle valve with a crack will also allow gas to drip out. Cleaning the parts and placing new gaskets on the bowl will stop fuel leaks.


Step 1

Turn the engine off and pull the spark plug wire off.

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Step 2

Place an adjustable wrench on the needle valve on the bottom of the float carburetor. Turn the wrench counterclockwise to loosen the needle valve and pull it straight down off the carburetor. Gas will begin to flow out of the bottom of the bowl. Pull the bowl straight down to remove it.


Step 3

Insert a screwdriver under the float and wedge it on the engine or a hose to raise it up and stop the flow of gas.

Step 4

Scrape the old gaskets off the top and bottom of the float bowl with a screwdriver.


Step 5

Spray a liberal amount of carburetor cleaner in the float bowl and scrub it with steel wool to clean it. Dry the float bowl with a towel. Spray the float bowl liberally with spray lubricant. Clean the needle valve tip in this same manner.

Step 6

Place a new gasket on the top and bottom of the bowl.


Step 7

Remove the screwdriver from the bottom of the float. Insert the bowl onto the float bottom and press it up. Insert the needle valve and hand tighten it clockwise. Tighten the needle valve fully with an adjustable wrench.

Step 8

Press the spark plug wire on the spark plug.


If gas flows out of the needle valve after cleaning and replacing it, the needle valve has a crack in it and needs replacing.


Do not operate an engine with a fuel leak. The fuel can become hot enough to combust on the exhaust and cause a fire hazard.


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