John deere walk behind w/ electric atart. runs good when running, sometimes you can crank and crank and crank, but will not turn over. I've replaced the sprk plug, fuel filter, air filter so far. Any ideas?

Http://autorepair.about.com/library/firing_orders/bl-fo-3804.htm

If you go to this web site ,it will have what you're looking for.
I've tried to create links for info such as this , but it doesn't seem to work. Sorry if the link does not work, but if you can get through all the typing, there's a complete diagram.

Diaphram in carb.may be bad, or very dirty. try a carb. cleaner, friend of mine used I think it's called-Sea Foam. hope it helps.