What was found
TURNBACK AFTER TAKEOFF, BOTH CENTER TANKS PUMPS FAULTED; BOTH DID NOT WORK IN EITHER AUTO OR MANUAL MODE. FOUND GFI TRIPPED ON BOTH LT AND RT PUMPS REST PUMP OPERATION CHECKS GOOD. REPLACED LT AND RT PUMPS, GFI RELAYS, PRECAUTIONARY PUMPS CK GOODIAW AMM 28-21-00.