In his written report the pilot said the airplane's engine quit 3 times in a 10 minute period. He said it re-started twice, but would not start on the third attempt. He entered a power off forced landing. During the landing roll, the airplane collided with a ditch and nosed over. The pilot stated he had enough fuel to make it to the airport which was 8 miles from the accident site. An FAA inspector and local police authorities examined the airplane and interviewed witnesses on scene. They reported finding a total of about 6 ounces of fuel in the airplane's fuel cells. They found no evidence of fuel spillage on the ground at the accident site. The FAA inspector found wrinkles in the fuel bladders and noted that airworthiness directives concerning the fuel tanks had not been complied with. The inspector reported the pilot had been using automobile gasoline in the airplane and the airplane's engine did not have an STC permitting the use of automobile gasoline. The inspector examined the airplane's engine and reported that no evidence of a mechanical failure or deficiency which could cause a loss of engine power was found.