What could be a potential cause of an engine backfiring?

A potential cause of an engine backfiring is when an exhaust valve sticks open. When an exhaust valve remains open while the combustion chamber is still firing, unburned fuel can escape into the exhaust system. This fuel can ignite in the exhaust due to the heat, resulting in a backfire.

In contrast, if a push rod is broken, it would most likely lead to a misalignment or failure of the valve operation, potentially causing engine roughness but not directly resulting in backfiring. A blocked float chamber primarily affects fuel supply to the carburetor and may cause the engine to stall or run poorly rather than backfire. Similarly, while a sticking inlet valve can disrupt proper airflow into the combustion chamber, it typically does not lead directly to backfiring; instead, it may cause poor engine performance or hesitation during acceleration. Therefore, the sticking of the exhaust valve is more directly related to the phenomenon of backfiring.