DURING A LOCAL PLEASURE SIGHTSEEING FLIGHT, THE ENGINE LOST POWER AND EVENTUALLY QUIT. THE PLT INITIATED AN EMERGENCY LANDING IN A PINEAPPLE FIELD WHERE THE ACFT COLLIDED WITH THE TERRAIN AND NOSED OVER. THE ACFT WAS FOUND TO HAVE APRX HALF A GALLON OF FUEL IN THE ENTIRE FUEL SYSTEM. THERE WERE NO MECHANICAL FAILURES OR MALFUNCTIONS NOTED DURING AN ENGINE RUN AFTER THE ACCIDENT. THE PLT STATED AFTER THE ACC THAT HE ESTIMATED FROM TANK OBSERCATION THAT THE ACFT CONTAINED ABOUT 10 GALS OF FUEL. THE PLTS HANDBOOK STATES THAT 3.5 GALS ARE UNUSABLE. THE PLT NOTED ON PREFLT THAT THE LEFT FUEL GAUGE READ FULL AND THE RT READ EMPTY. AN FAA INSPECTOR NOTED AFTER THE ACC THAT FUEL WAS RUNNING OUT OF THE LEFT FUEL VENT. THE WING SHOWED EVIDENCE OF IN FLT LEAKAGE. THE ACFT HAD A HISTORY OF A FUEL VENT LEAK. THE ACFT FLEW APRX 3/4 OF AN HOUR ON THE ACC FLT.