I have recently acquired a Merc 9.9 and I cannot get it started. The kill switch was checked for continunity and the plugs were checked for fire on another engine. Gas gets to the plugs but it does not attempt to fire. The engine attempted to start and turned over for a few seconds a few times but it will not start. It seems to be flooding. How can I check to see if the spark plugs are firing? I have tried grounding the plug to the motor ground but I do not see a spark. Is there a better way to check for spark? What else could be causing this engine not to start/fire?