On August 14, 2002, at 1130 Pacific daylight time, a Piper PA-38-112 Tomahawk, N4334E, sustained substantial damage during an off airport forced landing following a loss of engine power approximately one-half mile west of the Darrington Airport, Darrington, Washington. The private pilot and passenger sustained minor injuries. The airplane was being operated as a visual flight rules (VFR) personal pleasure flight under the provisions of Title 14, CFR Part 91, when the accident occurred. Visual meteorological conditions prevailed and no flight plan had been filed. In a written statement dated October 26, 2002, the pilot reported that shortly after takeoff from the Darrington Airport the airplane's engine "…momentarily lost power." He reported that the engine regained power, but again quit. This continued 15-17 times and the pilot elected to make an off-airport landing to a nearby field. He reported that during the landing rollout the airplane collided with a fence and drainage ditch resulting in substantial damage. In his written statement the pilot reported that the airplane lost power during the previous takeoff attempt. Following the loss of power, and aborted takeoff, the pilot completed a run up and full power check with no noted anomalies or malfunctions. Following the power check, the pilot initiated the second takeoff attempt (accident flight). Post accident examination of the aircraft by maintenance personnel from Aviation Inspection and Repair, Inc, disclosed that the gascolator gasket found on the accident airplane was the incorrect size. The gasket measured 1-3/8 inches (inside diameter) by 1-15/16 inches (outside diameter). According to Piper Aircraft, the airplane manufacture, the gascolator gasket (part number 462-049) measures 1-7/8 by 2-3/16 inches respectively. Maintenance personnel reported that the undersized gasket allowed the passage of air into the closed fuel system resulting in irregular fuel pressure to the engine (report attached). Maintenance records indicated that the aircraft's last inspection, an annual inspection, was completed on June 15, 2002.