On July 20, 1994, at 2103 central daylight time, a Cessna 175, N7101M, registered to Joaquin Merino of Pawnee, Illinois, and operated by a private pilot, experienced a total loss of engine power. During the forced landing, the airplane impacted a residence. The airplane sustained substantial damage. The pilot received serious injuries. One occupant of the residence received minor injuries, four others in the residence reported no injuries. The personal 14 CFR Part 91 flight was operating in visual meteorological conditions. No flight plan was on file. The flight departed Rockford, Illinois, at 1900. This report is prepared from a written statement from the pilot and a personal interview recorded by a Federal Aviation Administration inspector. The pilot stated that he had fueled the airplane prior to his departure from the Nichols Airport at Granite City, Illinois, for the flight to Rockford, Illinois. While he was unable to state exactly the amount of fuel on board the airplane on departure from Rockford, he stated that he paid for 10 gallons of fuel to be added to the tanks. A check with the FBO at Rockford produced a fuel ticket dated July 20, 1994, at 1630, indicating 10 gallons of fuel charged to N7101M. The pilot stated that he looked in the fuel tanks prior to departure from Rockford, but he could not tell exactly how much fuel was on board at that time. The pilot's estimation of the endurance of the airplane with full tanks was 4 hours 0 minutes. He indicated that he did not use the fuel gages to determine the fuel quantity remaining in the airplane, but relied on a stopwatch. He stated that the flight to Rockford had taken 2 hours and 10 minutes. He said that the duration of the return flight was 1 hour and 50 minutes until fuel exhaustion. The pilot stated that his intention was to return to Nichols Airport, but that he diverted to land at Saint Louis Regional Airport when the airplane began to lose power due to fuel exhaustion. He stated that he felt that there should have been about one hour endurance at that time. An examination of the airplane at the accident scene revealed that the fuel system was intact, that there appeared to be no loss of fuel at the scene, and there were no fuel stains on the airplane. The fuel tanks were drained and found to contain only unusable fuel at the accident location.