On May 24, 1999, about 1705 Pacific daylight time, a Travis Kitfox, N149BT, registered to and operated by the pilot, was substantially damaged during an off-airport forced landing following a sudden loss of engine power. The accident occurred approximately one mile northeast of Carnation, Washington. The private pilot and his passenger were uninjured. No flight plan was filed and visual meteorological conditions prevailed for the 14CFR91 personal/pleasure flight. The flight originated from Sequim Valley airport, Sequim, Washington, approximately 1405 PDT. The pilot reported that while in a cruise flight configuration the engine started to lose power and eventually quit. The pilot executed a forced landing in a crowned hay field. Upon touchdown, the aircraft bounced, momentarily became airborne, then touched down a second time. In an effort to stop, the pilot intentionally ground- looped the aircraft. The aircraft came to rest in a irrigation canal that paralleled the hay field. The aircraft's main landing gear and both wings were substantially damaged. The pilot stated that a post accident inspection of the engine revealed a large crack in the impulse line running from the engine's crankcase to the pulse fuel pump. A conversation with a technical representative from Rotax Engines revealed that a breech of this type in the impulse line would result in a failure of the pulse fuel pump.