One time I could not get my CEN engine to run AT ALL...it would "kick" the piston up and down a few times but would not start. I took the glow plug out and checked it...was glowing dark red...

SO I proceded to take the entire engine apart and clean it.

Put everything back together...put a new air filter sponge on it....adjusted the carb to the factory setting...still would not start.

Put a new battery in my glow igniter so the plug would glow BRIGHT red...started on about the 4th pull!

I find the engine starts on about the 4th pull with the glow plug BRIGHT red.

Also I have the trim adjusted to so the throttle is at about 1/4 open when I'm trying to start...Just make sure your ready when it fires or put your foot in the way so the car wont take off down the street with your glow ignitor sticking out.