I have a 2000 rancher that will start and idle but if you try to give it gas - it just dies. Push the starter button and it fires right back up. I have drained all the gas and replaced with new. Still the same idles - but nothing more.

 

I would say your main jet in your carb is either plugged or screwed too far in/out, the main jet delivers fuel through the carb from about 1/3-full throttle. If you are familiar with your carburator i would suggest taking it off of your machine and take the float bowl off, then look for 2 screws between the floats. the smaller will probably be the pilot jet and the larger will be the main jet. just from observing these will give you an idea if the main jet is screwed all the way in or out, i would try screwing it in all the wain then out about 2 1/2 turns, then move in 1/4 turn till it will allow you to throttle it. Also: what has been going on with the machine, has it been setting outside? has it been setting with gas in it all winter? any general information on when it stopped running would be great. hope it helps.

 

happens to me every now and then when mud gets in the carb.
take off the carb, clean it out good (be sure to get the bowl and the jets)

 

Happened to me once, I had to drain the water out of my airbox and change the oil, then clean the carb,