As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
L ENGINE FUEL FILTER EICAS MESSAGE CAME ON DURING CLIMB. EICAS MESSAGE CAME ON AND OFF SEVERAL TIMES AND REMAINED ON THROUGHOUT. MOST OFF THE FLIGHT. LT ENGINE VIBRATED AND VIBRATION INCREASED DURING DESCENT COMPLIED WITH NON-NORMAL AND NORMAL CHECKLISTS DECLARED AN EMERGENCY AND RETURNED TO CAN. FILTER ELEMENT CHECKED NORMAL, NO CONTAMINATION. INSTALLED THE NEW FUEL FILTER ELEMENT. WIRING CHECK NO ABNORMAL FOUND. REPLACED FUEL FILTER DIFFERENTIAL PRESSURE SWITCH. PERFORMED L ENG HIGH POWER RUN, ALL PARAMETERS NORMAL.