I have a poulan pro 700 54 inch cut riding tractor. I noticed it quiting on me a few times the last few weeks, but it started up when I tried to start it. This time I started it, it ran for a few minutes then died. It has not started since. It does not seem to have a spark at the plug, but am not sure since I have to be on the seat to try and start it. I unpluged the seat switch and tried it because my dads mower will start with the seat switch unpluged and no one sitting on it. No luck. What should I check first an how?