A PIPER PA 28R-200, COLLIDED WITH WIRES DURING A FORCED LANDING AFTER SUSTAINING A LOSS OF ENG POWER. THE AIRPLANE LOST ENG POWER WHILE FLYING ABOUT 700 FEET ABOVE THE GROUND LEVEL. THE PLT THEN SWITCHED FUEL TANKS AND THE AIRPLANE REGAINED ENG POWER. THE ENG LOST POWER AGAIN AND THE PLT WAS FORCED TO LAND. THE AIRPLANE STRUCK WIRES DURING THE FINAL APPROACH, AND THEN STRUCK A TRUCK INJURING THE DRIVER. THE PLT INDICATED HE COMPLETED HIS PREFLIGHT CHECKS BEFORE TAKEOFF AND NOTED THERE WAS NO FUEL IN THE AIRPLANE'S RIGHT TANK, BUT ADEQUATE FUEL IN THE LEFT TANK TO COMPLETE THE FLIGHT. THE AIRPLANE LEFT FUEL TANK HAD ABOUT 15 GALLONS OF FUEL REMAINING. THE RIGHT WING WAS SEVERED AND THE RIGHT FUEL TANK RUPTURED. THE PILOT REPORTED THAT HE HAD SWITCHED TANKS BEFORE THE ENGINE FAILURE WHICH CAUSED THE ENGINE TO FAIL DUE TO FUEL STARVATION. THERE WAS NO EVIDENCE OF ANY FUEL SPILL AT THE ACCIDENT SITE. AN ENG EXAM AND OPERATION TEST WAS CONDUCTED. THERE WERE NO MECHANICAL DEFICIENCIES OR MALFUNCTIONS NOTED. ON THE DAY BEFORE THE ACCIDENT, THE ENG QUIT DURING A FLIGHT AND WAS RESTARTED. THE PLT DID NOT DETERMINE THE CAUSE OF THE INITIAL ENG FAILURE.