I'm not familiar with atv's cooling systems, but if you open up your radiator cap while the bike is just warming up, you should see coolant flowing through the radiator neck. You mention something about the coolant spewing everywhere, well there is pressure in the radiator, but that doens't mean your pump is working?

 

I just went through this with my 00 sp500. The problem was an air bubble trapped in the cooling system. I started the engine, and winched the machine up at an angle and shoot it back and forth. I followed that by reving the engine with no radiator cap on and made sure the coolant was circulation and saw little air bubbles coming up. Now it runs great and my fan doesn't kick on as much.


Jim