What was found
SHIP 6704 -FIRE/DE- DURING LEFT ENGINE START, LEFT ENGINE EXPERIENCED A TAIL PIPE FIRE. FLIGHT RETURNED TO THE GATE AND FIRE EXTINGUISHED ON ITS OWN ON SHUTDOWN. ARFF RESPONDED BUT NO ACTION WAS TAKEN. AIRCRAFT WAS CLEARED TO BE TOWED BACK TO THE GATE. CORRECTIVE ACTION: REPLACED LEFT ENGINE EEC AND ENGINE BORO. REPLACED #5 SPOILER AND CANOE FAIRING, SUBSEQUENTLY CHANGED LEFT ENGINE.