Can you post a picture of your setup? There could be so many things that affect the engine.
Maybe your fuel tank is not at the correct location. The tubes coming out of the tank should be about level with the centerline of the carb. If there was that much fuel on the floor, then it sounds like it is siphoning fuel even if you aren't cranking the engine. All around, it sound like the engine is getting enough, (too much?), fuel but not enough plug heat. Check the battery on the glow ignitor. The plug needs a full 1.2 or more volts. A weak battery will not heat up the plug enough to get a new engine started. If all else fails, you may want to consider sending the engine back for service.

Jesse