On August 7, 2010, at 1530 eastern daylight time, an experimental amateur-built Glines Sportsman 2, N546SG, made a forced landing at Morrisville-Stowe State Airport (MVL), Morrisville, Vermont. Visual meteorological conditions prevailed and no flight plan was filed. The local personal flight was operated in accordance with 14 Code of Federal Regulations Part 91. The certificated private pilot and one passenger were not injured, and the airplane sustained substantial damage. The flight departed MVL at 1515. The pilot stated that during climb out, he noticed the airplane was not climbing as fast as normal. He turned crosswind between 1,500 and 1,800 feet mean sea level, and continued to climb out on the downwind leg. He heard an audible annunciator warning from the panel with the message, "check fuel pressure," multiple times. He scanned the instruments and noted the fuel pressure indicator was in the red, indicating there was a very low or no fuel pressure. The pilot recycled the boost pump from the on position to the off position, and back to the on position twice, with no effect on the fuel pressure reading. The circuit breakers were checked and they were all in. The mixture, prop, and throttle positions appeared to be in normal climb positions but he noted a decrease in rpm and manifold pressure. The pilot stated he normally maintained 2,400 rpm over 24 inches of manifold pressure with the mixture full rich, but he noticed that the rpm and manifold pressure were declining and the engine was continuing to lose power while the annunciator panel continued sound the warning, "check fuel pressure." The pilot called the departure airport on the common traffic advisory frequency, reported the problem, and informed them he was returning to the airport. He monitored the instruments, the engine continued to lose power, and he made a direct approach to runway 1. The pilot maintained 80 knots and lowered full flaps when he was able to reach the landing threshold. He initiated a flare, the main landing gear touched down hard on the runway, followed by the nose landing gear. It felt as if the nose gear had caught on something or possibly blown a tire. The pilot then pulled back the control stick to get the nose wheel off the runway. The airplane slowed down, the nose wheel came down, caught on something and began to slide and veer to the left and off the runway. The airplane would not respond to brake or rudder inputs and the nose landing gear dug in the ground. The airplane subsequently nosed over and came to rest inverted. The airplane was equipped with a Lycoming YIO-360-EXP, 210-horsepower engine. The engine had accumulated 108 hours since new and 23 hours since the airplane's most recent condition inspection, which was performed on July 4, 2010. Subsequent examination of the airplane revealed that it had received structural damage to the airframe. The nose landing gear was bent aft and the landing gear tire was blown. The engine cowling remained in place and the engine remained attached to the firewall. The propeller remained attached to the propeller crankshaft flange. One propeller blade was bent aft about 20 degrees at mid span and exhibited leading edge gouges and chord-wise scoring near the propeller blade tip. The remaining propeller blade was bent aft and exhibited leading edge gouging at the propeller blade tip. The nose landing gear was bent rearward and the landing tire was blown. The engine cowling and propeller spinner were removed. The upper sparkplugs were removed and the engine was rotated by turning the propeller by hand. Suction and compression was observed from all four cylinders. Spark was observed from the left magneto ignition leads. The left magneto was the only magneto equipped with an impulse coupling. The remaining sparkplugs were removed and oil was observed to drain from the No. 2 cylinder. The sparkplug electrodes exhibited dark gray coloration and worn normal condition. The sparkplugs were reinstalled and the ignition leads were reconnected. The fuel selector was placed in the "BOTH" position and the boost pump switch were placed in the "ON" position. The pump was heard to operate and positive fuel pressure and fuel flow was observed on the aircraft instruments. The airplane was moved to an aircraft tie down area and the aircraft tail tie down ring was secured to a tie down anchor. The engine was started three separate times and run at various power settings from 1,000 rpm to full power. The airplane fuel boost pump was used to start the engine, but remained off during the engine runs. The engine was reduced to idle power and shut down. The airplane was returned to a hangar and the fuel injectors were removed and reattached to the injector lines. The injectors were placed over containers to catch the fuel from the injectors. The boost pump was turned on and fuel flow from all injector nozzles was confirmed with the fuel selector in the both, left, and right positions. The containers were emptied and the boost pump was turned on again allowing fuel to flow into the containers about halfway. The containers were compared and appeared to contain about even amounts of fuel. The engine driven fuel pump, the hose from the pump to the fuel injector servo, the fuel injector servo, the hose from the servo to the fuel flow transducer, the fuel transducer, the hose from the transducer to the fuel flow manifold, the fuel flow manifold, the No. 4 injector nozzle tubes and the No. 4 injector nozzles were removed from the engine. They were then reattached to each in their original sequence and given to a Federal Aviation Administration inspector, who shipped the components to Lycoming Engines for further examination. Lycoming Engines did not have the equipment to conduct the examination and the components were subsequently shipped to Precision Airmotive LLC, and examined under the supervision of an NTSB investigator. No anomalies were found. The Advanced Flight Systems AF3000 multifunction display (MFD) was removed from the airplane and sent to the NTSB Vehicle Recorder's Laboratory for readout. Download of the MFD revealed that the last flight was normal until 1521, when the fuel pressure data became erratic. The data exhibited an increasingly erratic behavior until the flight ended about 1528. The fuel pressure data from the entire recording was examined. No other anomalies of erratic behavior were found. The reason for the loss of fuel pressure was not determined.