According to the pilot, shortly after takeoff he noticed that there was no movement on the header tank fuel float gauge. He went on to say that the fuel float gauge then started to move "down quickly", and since he still had the airport insight, he decided to turn back and conduct a precautionary landing. As he approached for landing he "raised" the nose of the airplane to slow down; but became "too low and too slow" and the airplane collided with a road adjacent to the airport. The airplane sustained substantial damage to the fuselage and wings. Examination of the fuel float gauge by a Federal Aviation Administration inspector did not reveal any anomalies. In addition, the pilot reported there were no pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.