Make sure you are not trying to crank the engine in a flooded condition. Just remove the glo plug, and spin it through about 5 - 10 flips with the glo plug out. You might want to put a cloth over the hole for the plug for the first couple of spins in case it spurts out fuel. I found that it is easy to overprime the motor. Just 1 or 2 rotations after the fuel goes into the main needle is all it should take to prime it.