THE PILOT REPORTED THAT WHILE CRUISING IN THE EXPERIMENTAL AIRPLANE HE SMELLED THE STRONG ODOR OF FUEL FUMES IN THE COCKPIT. WHEN HE SWITCHED FUEL TANKS TO ABATE [THE] FUMES ALL ENGINE POWER WAS SUDDENLY LOST. UNABLE TO RESTART THE ENGINE, THE PILOT INDICATED HE BEGAN CONCENTRATING ON MAKING A FORCED LANDING. ON FINAL APPROACH TO A PARKING LOT, THE AIRPLANE COLLIDED WITH UNOBSERVED POWER LINES AND NOSED OVER. AN EXAMINATION OF THE AIRPLANE REVEALED NO EVIDENCE OF ANY MECHANICAL MALFUNCTIONS WITHIN THE ENGINE. FUEL WAS FOUND IN THE LINES BETWEEN THE ENGINE DRIVEN FUEL PUMP AND FUEL SERVO, AND IN THE MANIFOLD ASSEMBLY. EVIDENCE WAS ALSO FOUND OF PREIMPACT FUEL LEAKS (SEEPING AND STAINING) NEAR FUEL LINES AND FITTINGS IN AIRFRAME STRUCTURE AFT OF THE FIREWALL. THE LAST ANNUAL INSPECTION WAS ACCOMPLISHED BY THE AIRPLANE'S PREVIOUS OWNER.