Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Weight And Balance; Inflight Event / Encounter Fuel Issue
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; Flight Crew Inflight Shutdown; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
Enroute from ZZZ to ZZZ1; shortly after leveling off at cruise altitude; we received an IMBAL (imbalance) message and saw that our right fuel tank had 1;000 lbs less than the left tank. We had just turned off our center fuel pumps a few minutes prior. We performed the IMBAL checklist which then led us to the Fuel Leak Engine checklist. By this point it was decided that the safest course of action was to return to ZZZ. We requested priority handling and were cleared direct to ZZZ and were given a descent clearance. We shut down the #2 engine per the Fuel Leak Engine checklist. We also performed the One Engine Inoperative Landing checklist; the Non-Routine Landing Considerations checklist; and the Overweight Landing checklist. I was the Pilot Flying until downwind; at which time the Captain took the controls and landed the aircraft. We stopped on the runway and had the firefighters check out the aircraft. Everything looked ok to them and we were cleared to taxi to the gate. The Captain made an AML (Aircraft Maintenance Logbook) entry for the suspected fuel leak and overweight landing.The only causal factor was the mechanical irregularity of the right fuel tank showing 1;000 lbs less than the left; which gave us the IMBAL message.
B737-800 First Officer reported a fuel imbalance message in flight; causing an in-flight shut down of the #2 engine and a return to the departure airport.