How can I fix my lawn mower, yardman, 11a-573E452?

My yardman model#, 11a-573E452, will just die on me. I was mowing my yard and got more than half way done when the mower started to bog out a bit then completely die. The lawn mower would start right back up and continue to mow for a little while when the lawn mower then start to bog out again and then completely die. I thought I ran out of gas but still had almost a full tank. Every time I restarted the lawn mower it would not run for as long. Now the yardman lawn mower will start every time, but then suddonly die. It sounds like there is no gas getting to the engine. Why wont the motor run, what would make the lawn mower judst die?