I have a 2001 Polaris Sportsman 500HO.
I can be riding for awhile and the engine will stop getting fuel. I can try to get it restarted and it will spit and sputter. I figured out that if I add pressure to the fuel tank by blowing into the vent line it will start right up and run fine for 10 minutes to and hour and then do it again.
This problems happens with the gas cap on or off, I thought maybe the vent line was pluged.
I'm thinking the fuel pump is losing it prime or suction. Not sure how it works!
I could use some help to get me starting corretly again. It sure looks bad blowing into that vent line hose out on the trails!

 

There is no electric fuel pump on the 500. Sounds like a tank vent line is clogged. When this happens the tank gets a vacuum and it will die until you take the cap off. This is a very common problem.

 

Taking the cap off doesn't fix the problem. I have to pressurize the tank to get it to start.
Almost as if there is a clog or air in the line that has the have the pressure to pass the fuel along. Sometimes I can ride for 25 miles or more before it acts up and other times just a mile or so.
On the 4 stroke Sportsman the fuel pump is at the lower left side of the fuel tank. Just above and behind the front wheel

 

I was meaning to say it does not have an electric pump. I know it has a mechanical pump. It could be going bad but they are pretty much bulletproof.

 

You may have a bad filter--you did not indicate if you had checked or changed that--or your pickup in the tank could be contaminated. Just other thoughts.

 

fuel pump works on a vacume. you always pull the gas line to the carb off the fuel pump when it starts giving you the promleb to see if the pump is spitting out gas. just a thought.

 

I would replace the filter first if you havent yet and if you still have problems I would rebuild or replace the fuel pump also make sure vaccum line from motor to pump isnt damaged in anyway