What was found
AT CRUIRE AT FL 340 HAD A LT ENGINE FIRE (L ENG FIRE) AND OVERHEAT (L ENG OVERHEAT) INDICTION ON EICAS , LT FIRE HANDLE AND LEFT CONTOL LEVER. NO UNUSUAL LT ENG INDICATIONS OR VIBRARATIONS OBSERVED., LT EGT REMAINED WITHIN LIMITS ENTIRE TIME. FOLLOWED QRH/QRC WHEN LT THROTTLE WAS RETARTED FIRE INDICATION WENT OUT & SHORTLY AFTER LT OVHT WARNING ALSO WENT OUT. EMERGENCY DECLARED RETURN TO MEMPHIS WAS UNEVENTFUL. INSPECTED LT ENGINE FOR LOOSE OR DAMAGED DUCTING OR SENSE LINES NO DEFECTS NOTED IAW AMM 36-11-01-6 . PERFORMEMED ENGINE FIRE & OVERHEAT DETECTION SYS TEST IAW AMM 26-11-00-5. NO DEFECTS NOTED STILL NEEDS MOVE TROUBLE SHOOTING. DURING LEAK CHECK OF #1 ENG BLEED FOUND LEAK AT PRSOV AFT COUPLING & AIR SUPPLY DUCT. PERFORMED AFLOTS SYS TEST. TEST PASS. RAN ENG @ 90% N1 WITH FULL PNU & ELEC LOAD FOR 10 MIN. NO FAULTS. ALL IND NORM.