To change the needle and seat on a 6.0- hp Briggs Quantum engine, you will need to first locate the carburetor. Remove the carburetor from the engine, then disassemble it to access the needle and seat. Replace the old needle and seat with new ones, then reassemble the carburetor and reinstall it on the engine.
Front of the engine screwed to the carburetor
To clean the float needle on a 16.5 HP Briggs and Stratton engine, first, remove the carburetor from the engine. Disassemble the carburetor to access the float and needle assembly, then carefully remove the float and needle. Clean the needle and seat with carburetor cleaner and a soft brush to remove any debris or varnish. Reassemble the components and reinstall the carburetor, ensuring all connections are secure.
Clean out the carburetor with gas, the reason it wont keep running is its not getting enough gas through the carburetor.
it may not have one. If it does it will be located on the fuel line between the fuel tank and the carburetor.
You can find the carburetor diagram for a Briggs and Stratton 4 hp engine model number 095212 in the service manual specific to that engine model. Additionally, Briggs and Stratton's official website often provides parts diagrams and manuals that can be downloaded for free. Alternatively, you can check online parts suppliers or forums dedicated to small engines for accessible diagrams and troubleshooting advice.
check your coil out
Clean the carburetor with special attention to the high speed jet and fuel passage.
mower carbs built since around the mid nineties are non adjustable, except for idle speed,
Three things you want to look for: dirty/clogged ful filter; faulty spark plug; carburetor setting.
You didn't say what engine model or carburetor you have, but you can go to http://outdoorpowerinfo.com/repairs/ and see if any of the pictures there look like yours.
how to Change oil on a Briggs and Stratton 6.75 HP