Briggs & Stratton Float Type Carburetor Service

Learn how to check, clean and replace the float type carburetor on a Briggs and Stratton Quantum 3.5HP Engine.

Tools/Parts Required 

  • Carburetor Cleaner
  • Flat Head Screwdrier
  • Needle Nose Pliers
  • Socket Wrench - 8mm, 10mm & 13mm

Step 1.

Firstly we start by removing the air filter and backing plate, being careful not to lose any gaskets or rubber hoses. Once these are removed the carburetor should be clearly visible. Remove the two mounting bolts and twist sideways to remove the throttle linkage.

Step 2

Next the fuel line will need to be removed, take note of any rubber seals when removing the carburetor, as these are important and must be in the correct position when everything is reassembled.

Step 3

Once the carburetor is removed you may remove the bottom bolt which secures the bowl, once this is undone you can inspect the bowl and float. Generally a clean carburetor, with some dirt in the bowl, can be cleaned with part cleaner and an air compressor; if the carburetor is full of green crusty gunk its likely that even with a through clean it will not run as desired. When inspecting the carburetor make sure the float is not cracked or full of petrol and check the jet is not sticking. If your carburetor was leaking check the rubber seal between the bowl and the body, as well as the washer on the bolt which secures the bowl. Once the carburetor is cleaned you may reassemble, being mindful to not get any dirt inside.

Step 4

You may now reassemble the lawn mower. If your lawn mower has a choke it is usually easiest to install correctly with the throttle in full forward position. If the throttle is in the wrong position the choke may not function or the throttle will not have full range of movement.


  1. Very informative.
    Just one question. I cleaned the Jets, but I couldn’t clean the jet in the carby body that is slightly raised. It was really blocked.
    Looks as though it goes through to the idle mixture screw.
    All I could do was get some wire in only about 2-3 mm.
    Any ideas would be appreciated!
    Cheers Steve..

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