On December 8, 1994, at 1500 mountain standard time, a Cessna 180, N1594C, experienced a loss of engine power while in cruise flight. The pilot initiated a forced landing to an open area near Lonetree, Wyoming, where during the landing roll, the airplane collided with the rough terrain. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the airline transport pilot, the sole occupant, was not injured. The flight had departed from Lander, Wyoming, on December 8, 1994, at 1330, and was destined for Salt Lake City, Utah, on a personal flight. During an interview and subsequent written statement, the pilot reported that he was in cruise flight at 10,000 feet mean sea level with the throttle set at 13 inches and the propeller set at 2,400 rpm. The pilot stated that he made no power adjustments for some time prior to the engine suddenly losing power. The pilot was unable to regain power to the engine and a forced landing was initiated to an open field where during the landing roll, the airplane collided with the rough terrain. The airplane was moved to a secured location and the engine was prepared on a stand for a test run. The mechanic performing the test run stated that the engine would start up immediately but would not remain running for long and lose power. When the engine lost power, fuel was noted to overflow from the carburetor. The carburetor was removed from the engine to be bench tested. It was noted that the Marvel Schebler carburetor had been overhauled on June 14, 1993. On March 10, 1994, the logbook entry states that the engine O-470-J was removed and a modified O-470-50 (520 Cu in) with the P. Ponk converted carburetor was installed. At the time of the accident, the engine had accumulated a total time of 136.9 hours since the overhaul, and 62 hours since the last annual inspection. During the carburetor bench test, another P. Ponk converted carburetor was used as a master to compare the two. The accident carburetor was found to operate within five pounds of the master carburetor in all ranges of power from idle to 1,300 rpm. After the bench test, the carburetor was visually inspected. All areas checked were found within normal operating specifications. During the inspection of the floats, it was noted that an area on the inside of one of the floats exhibited a light scoring on the brass. It was also noted that a light scoring mark was visible on the inside of the bowl that was located one and three-eights inch down from the top of the bowl, and approximately one-half inch long. The floats positioned in the bowl were slightly off center. The bracket that attaches the floats appeared to be tight and secured. After the bench test of the carburetor, another carburetor was placed on the engine. It was reported that the engine started immediately and ran without complications. The P. Ponk conversion consists of a larger venturi and main fuel discharge nozzle.