What was found
DURING FLIGHT USING FUEL MANUAL PROCEDURES, WE WERE UNABLE TO TURN OFF THE TAIL TANK PUMPS WHEN THE TANK WAS EMPTY. NO ALERTS WERE ANNUNCIATED. PHONE PATCHED AND ACARS WITH GOC/MOCC. IAW QRH AND MOCC WE PULLED CIRCUIT BREAKERS ASSOCIATED WITH QRH FUEL PUMPS LOW. PUMP CONTINUED TO INDICATE THAT IS WAS STILL OPERATING. MOCC SHOWED IT WAS STILL RUNNING AS WELL. OUT OF AN ABUNDANCE OF CAUTION, THE DECISION WAS MADE TO DIVERT TO NRT. R&R AFSC IAW AMM 28-08-03-4. R&R FSC FOR PRECAUTION IAW AMM 28-08-01-2. DID FSC R-T-S TEST AND PASSED IAW AMM 28-08-01-5. ALL PUMPS COULD CONTROL BY FUEL CONTROL PANEL WHEN MANUAL MODE.