You are going to have to test to find out if it is fuel or ignition related. Have many questions which you will need to answer before giving instructions as to how to proceed. The manual at the end of this post may help you.
1. When it quits, can you restart immediately?
2. If No restart have you checked for spark, if so how did you test?
3. If No restart, but have spark, spray carb cleaner into airhorn, will it fire?
4. How mechanically experienced are you?
5. To test the fuel solenoid, hold your hand n solenoid and turn key to on position. You should feel the solenoid click.
Remember, you are our eyes and ears and must paint us the best picture of what you are seeing and hearing.