I've pretty much only worked with Kohler and Tecumseh engines for the last 26 years so I have to plead a bit ignorant on Briggs but, for the flywheel does Briggs use a straight key or a woodruff key? If it's a woodruff key then to be sure the key is not sheared the flywheel will have to come off. Also, if this engine has a pulse style fuel pump check the pulse line for fuel. If there is fuel there, you need a new pump.