What else could be wrong? ?

I have a powerbase 3.5hp lawn mower engine number sl1p60f. I've taken the carb out and cleaned it all. Cleaned the magneto and ignition coil, changed the spark plug and get a blue spark. It was outside all winter and water got into the carb. Air filter is all clean, fuel filter is clean and I've changed the fuel. Still can't get it running. What could be wrong with it?