What was found
NR 1 ENGINE AFT FUEL PUMP LOW PRESSURE LIGHT INTERMITTENTLY ILLUMINATED AT CRUISE FL360 WITH 4200 LBS IN TANK. ACFT GROUNDED. OPENED THE CIRCUIT BREAKER ON P92 PANEL AND ATTACHED MIG 51 A D1 IAW AMM 28-22-41-000-801 STEP G.(3). PERFORMED ALTERNATE DEACTIVATION PROCEDURES IAW ASAM 5-07-01, TABLE 3 ITEM 3. REMOVED THE NR 1 AFT BOOST PUMP IAW AMM 28-22-41-000-801. INSTALLED A NEW BOOST PUMP REF B737-800 AMM 28-22-41-400-801. CLOSED CIRCUIT BREAKER ON P92. ACCOMPLISHED FUEL BOOST PUMP OPERATIONAL TEST FOR NR 1 AFT BOOST PUMP. OPS AND LEAK CHECKED OK IAW AMM 28-22-41-710-801.