According to the pilot, the airplane lost engine power shortly after take off at a height of approximately 300 feet above the ground. He attempted a forced landing on a mowed, grassy section of airport property. During the landing, the left main gear sank into the muddy turf and separated from the airplane. The airplane skidded for approximately 180-feet resulting in damage to the left wing tip, propeller, right landing gear, and lower longeron on the right side of the fuselage. The pilot sustained minor injuries. He reported that shortly before takeoff, he switched the fuel selector valve to the fullest tank, but that the fuel selector handle did not set properly in its detent, cutting off the flow of fuel to the engine.