I got a poulan 3350 "Predator thingy" that will not run with a muffler on it. I cant even get it to fire with a muffler. The spark arrestor is clean, and there is no blockage in the muffler at all. We even tried a new muffler, and it will not run. The compression is fine, we rebuilt/reset the carb. Still nada! Any one ever had a similar problem? Thanx in advance for any help!