I have seen this happen....guy cranking a glow engine real fast with a electric starter. I told the fellow, let me try to start it. I let it set a few min for the glow plug to burn out excess fuel. Then I back bounced it and it started on first bounce. What is happening...the incoming fuel mix is cooling the glow plug too much. The faster you spin it...the more glow gets snuffed out. Capt,n P.S. 33 years experience with glow engines