Gas won’t transfer from carburetor to cylinder

I have installed a new fuel pump and a new carburetor and a new starter but the gas won’t transfer from the carburetor into the cylinder. When I put gas into the cylinder and then put the spark plug back in the cart starts to run but the Exhaust comes back out through the air filter. I tried spraying Quickstart through the air filter hose and then turned the engine over but the engine blew the gas back through the air filter hose. Any ideas on the problem??