cub cadet engine will not start

The engine on my lt1042 will not start . I have spark, compression [90 lb ] and fuel. When i squirt gas or either starting fluid in to carb the engine just backfires. I removed the carb and checked the float and all inward parts PLEASE HELP Dick B thanks

Back fire I am going to say either your carb needs cleaning (less likely) or valves are out of adjustment