Because the Eager engine is a hunk of junk, compared with the Briggs and Stratton engine found in other Craftsman products. I have the same mower, and it's failing again, dying immediately after it starts. I just took it in last summer for a complete tune-up, therefore, the carburetor should not already be faulty or clogged. It's been an unimpressive piece of equipment from the start. It may be your carburetor, which will probably require professional repair, unless you're handy.
PLB, July 2007