TWO DAYS BEFORE THE ACDNT, THE PLT HAD FUELED THE ACFT TO CAPACITY & FLOWN IT A SHORT DISTANCE TO HIS HOUSE AT A PVT AIRSTRIP. AFTER THE FLT, HE NOTICED FUEL ON THE TOPS OF BOTH WINGS, AFT OF THE FUEL FILLER CAPS. HE WAS AWARE THAT FUEL HAD LEAKED FROM THE THERMOS TYPE FUEL CAPS. DURING THE NEXT FLT, WHEN THE ACFT WAS ON AN ILS APCH TO THE DESTN ARPT, THE ENG LOST POWER FROM FUEL EXHAUSTION. THE PLT DESCENDED BELOW THE CLOUD LAYER & MADE AN EMERGENCY LANDING IN A PEACH ORCHARD, WHERE THE ACFT WAS DAMAGED. THE ACFT HAD FLOWN 3.63 HRS SINCE IT WAS LAST REFUELED. THE PLT RPRTD IT HAD AT LEAST 4.3 HRS OF FUEL ON BOARD AFTER THE LAST REFUELING. HE BELIEVED THAT SOME 5 TO 6 GAL OF FUEL HAD SIPHONED FROM EACH TANK. AD 68-13-03 REQUIRED AN INSPN OF THE FUEL CAPS FOR DRYNESS & HARDNESS AFTER EACH 100 HRS OF FLT. THE LAST ENTRY IN THE LOG FOR COMPLIANCE WITH THIS AD WAS IN 1985 AT APRX 2590 HRS. TOTAL AIRFRAME TIME ON THE DATE OF THE ACDNT WAS 2981 HRS.