Date: 201503
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Aircraft component: Fuel System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Weight And Balance; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed As Precaution; Flight Crew Diverted
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Start of an originating three-day; I arrived at the aircraft first so I started the preflight. We had an MEL for the fuel auto shutoff at refueling station; which required me (Captain) to discuss the procedures with the Fueler. I decided to do the walkaround since I needed to talk with the Fueler. After completing the walkaround and talking with the Fueler; I went back to complete my preflight flows. This MEL required me to do a continuing 'info' MEL logbook entry.  I completed my flows; which includes checking the crossfeed valve which checked normal. While enroute; I started to empty the center tank fuel.  When the center quantity reached 2000; I opened the crossfeed valve and saw that the crossfeed light remained out. I did a lights check and the light remained out so I changed both indicator lights. This didn't change the light indicator so I located the crossfeed valve circuit breaker; which was out. We completed the QRH Crossfeed Selector Inop Checklist.  There was no fuel imbalance at the completion of the QRH. I contacted Dispatch via ACARS and informed them of what we had and that the fuel balance was good. My F/O was the PF.  We discussed our options and; since our aircraft was operating normally; we decided to continue.  About 30 minutes after we contacted Dispatch; our fuel started to become unbalanced. I initiated a phone patch with Ops. When I made contact with Dispatch and explained what we had and our imbalance was increasing with no way to control; the Dispatcher and I decided to divert. I made a PA announcement and briefed the F/As.  We amended the Release to show the divert and proceeded to the airport. We did not declare an emergency at any time. We were overweight for landing and had a fuel imbalance of approximately 1100 pounds. I wrote up the crossfeed valve and overweight landing.


Second narrative: In cruise; the center fuel tank reached approximately 2000 pounds causing the Captain to open the crossfeed valve and turn off one center tank pump. We did not get an indication that the valve moved. Conducted a lights test and did not see the crossfeed valve illuminate. We replaced the bulbs to no avail. The valve tested fine on preflight. We ran the QRH and discovered the circuit breaker had popped. After a short period of monitoring; the left tank was drawing down at a faster rate than the right tank.


Synopsis: B737-700 flight crew dispatched with fuel system MEL reported related anomalies in flight that led to a precautionary divert to a nearby airport.