It's normally 98 percent fuel related, 2 percent plug related. Pull the carb and clean it up, and yes, certainly pull the air filter to see if it's hopelessly plugged up.Found this generator on Craig list. North Star 5500 PPG. Vary nice, garage kept. I fired it up this evening for the first time, put a space heater on it. Seems to be missing. What should I do?