FLC EXPERIENCED FALSE ENG FIRE WARNING.

Narrative

SHORTLY AFTER TKOF FROM FACT ENRTE TO GVAC WE HAD A FIRE WARNING INDICATION ON #1 ENG. THE ACFT HAD BEEN DISPATCHED WITH THE 'B' FIRE LOOP INOP ON THAT ENG. AS WE WERE RUNNING THE PROCS FOR THE PROB; I REQUESTED A LEVEL OFF AND INFORMED ATC; AND REQUESTED VECTORS FOR A POSSIBLE RETURN. AS WE WERE LEVELING OFF THE FIRE INDICATIONS WENT AWAY. ALL ENG PARAMETERS WERE NORMAL AT ALL TIMES; AND THE SYS SUBSEQUENTLY TESTED GOOD. I ELECTED TO CONTINUE CLB TO FL350; AND NO FURTHER PROBS WERE ENCOUNTERED. APPROX 3 HRS OUT OF GVAC WE CLBED TO FL390; AND SHORTLY THEREAFTER WE AGAIN HAD A FIRE WARNING. AGAIN ALL ENG PARAMETERS WERE NORMAL. I RETURNED TO FL350. THE WARNING REMAINED ON STEADY EXCEPT FOR A FIRE LIGHT IN THE FUEL SWITCH WHICH BLINKED CONTINUOUSLY UNTIL SHORTLY BEFORE DSCNT. UPON STARTING OUR DSCNT ALL FIRE WARNINGS WENT OUT. UPON TAXI IN I SHUT DOWN THE ENG. MAINT SWITCHED THE WIRING HARNESSES FROM THE KNOWN BAD LOOP 'B' TO THE 'A' LOOP FOR THAT ENG. WE CONTINUED ON OUR FLT TO KIAD WITHOUT ANY FURTHER INCIDENT.