On July 9, 1994, about 1530 eastern daylight time, a Cessna 172, N5233R, registered to Gordon Air Services, Inc., ran off the runway and collided with a fence while making a forced landing following partial loss of engine power at Peter O. Knight Airport, Tampa, Florida, while on a 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the private-rated pilot and one passenger were not injured. The flight originated at Tampa, Florida, on July 9, 1994, about 1525. The pilot stated he departed Tampa International Airport and was climbing to his cruise altitude when passing through 1,800 feet the engine lost about 600 rpm. Attempts to recover engine power were unsuccessful. He saw Peter O. Knight Airport ahead and descended for landing on runway 17. The landing to runway 17 was aborted due to excessive airspeed and altitude. A turn to the left was made for a downwind approach to runway 21. While landing on runway 21 he touched down about halfway down the runway at about 100 knots with half flaps extended. He could not stop the aircraft before over-running the runway and colliding with a fence. After the accident the engine was started and operated to 2,000 rpm where it ran roughly. The bottom spark plugs were removed and replaced with serviceable spark plugs. The engine was then started and operated normally to full power. Examination of the bottom spark plugs indicated the plugs were gapped over twice the recommended gap and that the plugs were fouled. The engine had a Supplemental Type Certificate complied with, allowing operation with automotive fuel. The owner stated they did normally operate with automotive fuel. The pilot stated he had just topped off the fuel tanks with 100 low lead aviation fuel before the accident.