The pilot/owner/builder completed a preflight inspection using the checklist he wrote for his airplane. He departed on his first solo flight in the homebuilt, jet-powered, Velocity Jet 900 airplane. He had no prior jet-powered airplane experience or training. After takeoff, the airplane climbed above traffic pattern altitude at "4 to 5 thousand feet-per-minute" and accelerated above 200 knots on the downwind leg of the traffic pattern. The pilot then reduced power to flight idle to descend and complete the traffic pattern for landing. The airplane was "low" on the base leg of the pattern, so the pilot advanced the throttle, but the engine did not accelerate, and continued to run at the flight idle setting. As the airplane approached the runway, "I got too slow, lost control, and crashed 100 feet short of the runway." Examination of the wreckage revealed that the fuel tank vent was clogged with dirt and insect remains. There were no other deficiencies noted.