I got a 3yr old stihl FS110RX (4mix). It will not start no matter what until after 20mins of pulling the string. It'll run fine and start fine again as long as you do it within half hour. Gas dribbles out the carb also when cranking. -I've changed the carb and that didnt help at all. -I have a spark outside the cylinder but dont know about inside the cylinder, if the cylinder pressure is putting out the spark. -I've adjusted the valves and it ran fine for about a week then this started. -I adjusted the valves at TDC, is that correct or is there some other spot to adjust at? -How do i check the coil resistance? there are three wires:blue(case ground), black(on/off)?, plug wire. This is the numbers on the coil: 4180 1301 a mc 4180 411 Anyother ideas?