My van stalled out while i was driving. i thought it was out of gas or something so i walked to the gas station, got some gas and put it in. i went to start it and it still wouldnt. it would turn over but it wouldnt fire up and run. so i opened up the hood and put a little gas in the carb and tried to start it again. this time it fired up but it wouldnt stay running. i assume it must have something to do with the fuel getting to the motor. my question is, what could be the problem and what do i need to do to fix it?