Ran well all last summer,but now it turns over but won't run,put gas in carb. And it run till that gas is used. This is an older riding mower and need some help.also is there a place on the net that I can find a manual and diagrams of motor

Sounds like a clogged fuel line. Empty your tank and take off the lines. Attach them to an air compressor and try to blow out whatever it is.

Sounds like carb problems, remove the carb bowl and inspect the fuel for contaminants.