On March 24, 1998, about 1345 eastern standard time, a Piper PA-28-180, N8490W, registered to 8490 W Enterprises Ltd., collided with terrain during a forced landing near Punta Gorda, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 instructional flight. The airplane was substantially damaged and the certified flight instructor (CFI) and student pilot were not injured. The flight originated about 1315 from Charlotte County Airport, Punta Gorda, Florida. The CFI stated that while flying over a grass airstrip during a training flight, he simulated a loss of engine power by reducing throttle. Carburetor heat was applied during the descent, and the engine was cleared two times by rapid throttle application. The student maneuvered the airplane to land on the grass runway and at the approach end of the runway, power was applied to go-around before touchdown. The engine responded with the tachometer indicating 2,500 rpm and the flight climbed to about 300 feet; at that time a total loss of power occurred. He advised the student to switch the fuel selector which was accomplished and the engine power was restored to 2,500 rpm, momentarily. The engine quit again, and due to the low altitude, he maneuvered the airplane toward a field. After touchdown, with the throttle still applied, engine power was restored just before contact with a mogule. The airplane then came to a complete stop and both exited the airplane. The student stated that before departure, she was advised by her instructor that during the flight, he would simulate a loss of engine power. The flight departed with full fuel tanks, performed airwork, then landed at the Charlotte County Airport and taxied about 10 minutes to familiarize herself with the airport. The flight then departed with the fuel selector positioned to the same tank as the initial departure airport, climbed to about 2,000 feet, and flew over the Shell Creek Airpark. The instructor announced his intentions of simulating the engine failure and did so by only reducing the throttle to idle. The student performed the emergency checklist and applied carburetor heat, turned on the auxiliary fuel pump, and switched the fuel selector from the "left" to the "right" tank. The student maneuvered the airplane to land to the north on the 2,600-foot grass runway and while on final approach, the CFI advised her to go-around. She applied full throttle and climbed to about 100 feet above ground level, where she removed carburetor heat, and accelerated to Vy( best rate of climb). The flight continued climbing to 250 feet above ground level where the engine quit. She positioned the fuel selector to the "left" tank and the engine responded momentarily, but quit again. The CFI landed the airplane in a field and during the landing roll with the throttle applied 1/2 way, the engine responded when the nose landing gear collided with a berm. The nose landing gear then separated and the airplane came to rest. A witness near the crash site reported hearing the sequence of events as described by the CFI and student. Examination of the airplane by an FAA inspector revealed adequate quantity of fuel in each of the fuel tanks with no evidence of contamination. The inspector did not check the gascolator due to the resting position of the airplane. According to an individual who helped recover the airplane, the gascolator did not contain any fuel when he checked it during recovery of the airplane. The left and right fuel tanks were drained and found to contain 17 and 15 gallons of fuel respectively; no contaminants were noted. The wings were removed to facilitate transporting the airplane. Examination of the airframe by a representative of the airframe manufacturer revealed no blockage of either fuel tank vent system. The fuel line at each wing root was placed in a container of fuel and the auxiliary fuel pump was operated with the fuel selector positioned to the respective tank. Fuel flow was noted through the selector valve, through the gascolator and the fuel pump. Disassembly of the gascolator revealed that the screen was missing. No discrepancies of the fuel delivery system from the tank outlet to the gascolator were noted for each fuel tank. Additionally, the auxiliary fuel pump was operationally checked and found to flow about 2 quarts per minute with no "head" pressure; which equates to about 30 gallons per hour. According to the specification for the pump, a required flow of 30 gallons per hour is required with no "head" pressure. The engine was removed from the airframe, placed in a test stand and found to operate normally.