If it is a 3.5HP a new set of diaphams will do the trick, they are located between the carb and tank. It is really inexpensive and easy to do
the problem is there is water are trash in the carb bowl. to fix this is easy just take the screw out that holds the bowl and spray carb cleaner in it and the inside of carb then make sure bowl i8s clean replace bowl and it will run fine
Check your carberator. Only need 3 things for the engine to work. Fuel, Fire, and Timing. Gotta be a fault in one of the systems.
I can answer this question...
How do i service a briggs & stratton mower engine that keeps stalling?