On November 4, 2000, at 1201 hours Pacific standard time, a Piper PA-28-140, N9986W, lost engine power, force landed in an open field, and collided with a berm approximately 6 miles east of the Livermore Municipal Airport, Livermore, California. The airplane was operated by the owners under the provisions of 14 CFR Part 91 as personal fight. The airplane sustained substantial damage. The private pilot was not injured. The certified flight instructor (CFI), who was acting as the safety pilot for the flight, sustained serious injuries. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. The flight departed Buchanan Field, Concord, California, at 1130, and was scheduled to terminate there. A Safety Board investigator interviewed the private pilot. He stated that the purpose of the flight was to conduct instrument approaches into Livermore. While on the ILS-localizer approach for runway 25R, the private pilot reported that he intended to switch from the right tank to the left tank, but moved the fuel selector handle to the off position. When he and the safety pilot attempted to move the fuel selector handle back to the left tank, it jammed. In the pilot's written statement to the Safety Board, he stated that he had been cleared for the ILS approach into Livermore. At 3,300 feet he was established on the localizer, and the safety pilot suggested that he switch the fuel tank from the left tank to the right tank. He thought that the position for the left tank was at the 9 o'clock position, and switched the fuel selector handle from the 3 o'clock position to the 9 o'clock position. The pilot indicated that the engine lost power. The safety pilot recognized that the first pilot had inadvertently shutoff the fuel. Both pilots attempted to return the fuel selector handle to the left fuel tank, but were unable to move the handle. The safety pilot took control of the airplane, declared an emergency, and landed in an open field. In the second pilot's written statement to the Safety Board, he indicated that he had accompanied the first pilot to act as the safety pilot for the tower en route IFR flight. He stated that about 3,300 feet the first pilot inquired if he should switch the fuel tanks. The safety pilot responded that was the procedure, and to continue checking for traffic that Livermore had identified for them. He stated that moments later the engine quit and he told the first pilot to switch back to the original tank. The safety pilot indicated that he could not reach the fuel selector due to where he was seated. He was seated in the right seat and the fuel selector is located on the lower left side of the cabin. He saw that they were losing altitude, declared an emergency, and picked a spot to make a forced landing. An officer from the Livermore police department interviewed the pilot at the accident site. The pilot stated that he had only flown the airplane "a couple of times" and he was trying to gain more experience flying the airplane. He further stated that he believed the fuel tank selector positions were "LEFT-OFF-RIGHT" and he moved the fuel selector handle too far to the left without verifying the positions by looking at the markings. The officer observed that the positions on the fuel selector are "OFF-LEFT-RIGHT," and that the fuel selector handle was pointing towards the "OFF" position. A Federal Aviation Administration (FAA) inspector interviewed the pilot. The pilot stated that the purpose of the flight was to practice IFR procedures. He was the pilot-in-command and had invited the second pilot along to act as a lookout pilot for the flight. The airplane was inspected at Plain Parts in Pleasant Grove, California, on November 22, 2000, by an FAA inspector. He observed that the fuel selector handle was in the "OFF" position. He moved the fuel selector to the "RIGHT" position and noted that it was difficult to move, "as in a lack of lubrication," however, he was able to rotate the handle with one hand. He then moved the fuel selector handle to the "LEFT" position and felt the same amount of resistance as when he had moved the handle to the "RIGHT" position. The FAA inspector then attempted to move the fuel selector handle to the "OFF" position. He was not able to rotate the handle to the "OFF" position without first depressing and holding down the "button" on the selector cover. He stated that the fuel control handle was difficult to rotate and required lubrication, but the system functioned properly.