Tractor stalls after approx. 15-20 of run time...

Question

It will start back up after 5 min. but only run for 2-3 minutes. I replaced the coil (6V pos. ground system) with one from Tractor Supply and the tractor won't start at all. Put the old coil back in and it fires right up. Is it a coil problem? The coil I bought is 6v IH coil but the terminals are on the opposite end. The coil for 12v systems looks just like the one in there now?????????