B757 CAPTAIN REPORTS #1 ENGINE QUITTING SHORTLY AFTER BEING STARTED. MAINTENANCE CAN FIND NO FAULTS. CREW FLIES TWO LEGS WITH NO PROBLEMS BUT ENGINE QUITS AGAIN AFTER START ON THIRD LEG; THE FLIGHT WAS SUBSEQUENTLY CANCELLED.

Narrative

AFTER PUSHBACK AND ENGINE START; THE #1 (LEFT) ENGINE SHUT DOWN. CALLED MAINTENANCE; WENT BACK TO GATE. CALLED MAINTENANCE. HE DEFERRED MAINTENANCE ACTION TO MECHANICS. WE TOLD THE MECHANICS WHAT HAPPENED. THEY STATED THAT THERE WERE NO EPCS MESSAGES OR FAULTS DISPLAYED AND DIDN'T KNOW WHAT COULD BE WRONG WITH ENGINE. DID AN ENGINE RUN AT THE GATE FOR 5 MINUTES; ENGINE RAN FINE -- NO FAULTS -- AND DID NOT SHUT DOWN. MECHANICS SAID THEY COULDN'T FIND ANYTHING WRONG WITH ENGINE; THEN LEFT TO TALK WITH MAINTENANCE. PASSED INFORMATION TO MECHANICS THAT PASSENGERS SEATED IN BACK OF AIRCRAFT WITNESSED FLAMES COMING FROM BACK OF ENGINE DURING START. MECHANICS THEN STATED THAT THEY WOULD TAKE AIRCRAFT AND DO FURTHER ENGINE RUN-UP AND INSPECTION. AFTER THAT; MECHANICS STATED THAT THE ENGINE DID NOT SHUT DOWN AND COULD NOT FIND ANYTHING WRONG WITH ENGINE AND SIGNED IT OFF TO GO. WE THEN FLEW TWO LEGS WITHOUT INCIDENT. ON THIRD LEG AFTER PUSHBACK; #1 ENGINE SHUT DOWN AGAIN AFTER ENGINE START; SAME AS BEFORE IN ZZZ; NO EPCS MESSAGES OR FAULTS OCCURRED. RETURNED TO GATE AND CALLED MAINTENANCE. FLIGHT WAS TERMINATED. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING INFORMATION: THE REPORTER STATES THAT MAINTENANCE EVENTUALLY CHANGED BOTH THE FUEL CONTROL AND THE SPAR VALVE BEFORE THE AIRCRAFT WAS RETURNED TO SERVICE. BOTH OF THESE ITEMS SHOULD HAVE TRIGGERED A FAULT MESSAGE IF THEY WERE MALFUNCTIONING.