What was found
AT FL 370 , THE NR 2 LEFT INNER PUMP FAULTED. PUMP FAULTED AND STRONG ACRED ODOR IN THE COCKPIT AND THE AVIONICS COMPARTMENT, ON DESCENT THE REMAINING THREE INNER PUMPS FAULTED AND FUEL FEED RESORTED TO OUTER TANK TO ENGINE. ACCESSED THROUGH THE COCKPIT FLOOR. NO SMOKE WAS PRESENT IN THE COCKPIT OR THE AVIONICS COMPARTMENT. REMOVED AND REPLACED LEFT INNER TANK PUMP 2 POWER SUPPLY RELAY 35QA IAW ESPM 20-46-50. PERFORMED AN OPS TEST IAW AMM 28-21-00-05, CHECKED OK. AIRCRAFT OK FOR SERVICE