placed this engine 40h777-0168-e1 in a old john deere had to install new key switch, solenoid, and rewire, engine has been starting up and running good then for some reason will not start now, checked for spark on both cylinder's none, disconnected the coil ground wire still no spark, any clues as what to look for in order to be able to start   
thanks in advance
AC
	
		
			
		
		
	
			
			thanks in advance
AC