Several things could make a carburetor backfire. The engine could be out of time. the carburetor could have a stuck float, or the engine could have a stuck valve.
Running too rich, timing off. Search your engine and "backfire"
It keeps your boat from exploding.
backfire timing off
A carburetor backfire flame arrestor Is a safety device intended to prevent inboard engine explosions.Prevents explosions on inboard gasoline engines.Prevents explosions on inboard gasoline engines
Prevents explosions on inboard gasoline engines.
Prevents explosions on inboard gasoline engines.
Prevents explosions on inboard gasoline engines.
Prevents explosions on inboard gasoline engines.
Prevents explosions on inboard gasoline engines.
Prevents explosions on inboard gasoline engines
Incorrect timing or plug wires connected incorrectly.
Prevents explosions on inboard gasoline engines