I found that if I crack the throttle a touch it fires right up. I discovered this after I completely flooded the crap out of it several times because it simply wasn't getting enough air along with the gas. Mine sounded exactly like yours though. It would try to start, but the more I tried the less it tried to start (ie - the more it got flooded). Once it is going it idles perfect with the trims that low, but mine needs more air to start - that's it.