What was found
AFTER BEING GIVEN LINE UP AND WAIT INSTRUCTIONS FROM KSAN TOWER, TOWER REPORTED A TAIL PIPE FIRE ON NR 1 ENGINE. UNITED CONFIRMED THEY SAW THE FIRE BUT WHEN POWER WAS REDUCED THE FIRE WENT OUT. NO INDICATIONS OF A FIRE IN THE COCKPIT. RAN QRH AND AFTER RECEIVING CONFIRMATION OF NO FIRE BY CRASH/FIRE/RESCUE TAXIED TO THE GATE. INSPECTED ENGINE IAW AMM 71-00-00-800-803-F00. NO DEFECTS NOTED. RAN ENGINE IAW AMM 71-00-00. NO FIRE NOTED ALL ENGINE INDICATIONS NORMAL.