sounds like a stupid-simple solution, but I had the EXACT same thing when someone tried hotwiring my truck and it blew the 30amp starter relay (or ignition or whatever it is. it's a red 30A one inside your fuse box on the passenger side wheel well inside your engine compartment.)
I tried EVERYTHING. they syphoned my gas, and left a gas can in my bed. so I said "oh, gas!" poured it in, but saw that it was TWO STROKE! so I dropped and drained my tank, changed my fuel filter and lines, spark plugs and wires, starter, ignition, and nothing worked. was about to junk the truck when I said "it's a shame because these old trucks aren't as electronically controlled as new ones. look how how little fuses there are.... ummm.... ARE YOU KIDDING ME?!" hahahaha a $2.89 relay.... learned my lesson.
