B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 193; Flight Crew Type 4552
Confusion; Situational Awareness
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Flight Crew Landed As Precaution; Flight Crew Diverted; General Maintenance Action
Aircraft
Taking off well above min fuel around 11;000 lbs and then climbing out I checked the FMC progress page 4 and our fuel landing at destination was 5.6 LB. Sometime climbing out of the 20s; captain pointed out that the FMC progress page 4 had us now landing with 3.6 LB. During the rest of the climb and level off we were investigating all possible causes. We checked all of our entries from route; performance numbers; flight plan; all waypoints; howgozit; and new howgozit. We reloaded winds; and added all distances from the flight plan and checked against the FMC. The fuel gauges matched what the FMC had for current fuel. We could not find a problem in the FMC that would be the cause for landing with 3.4 now showing at destination and dropping. Shortly our FMC dropped again to 3.2 causing a Rev fuel message to display. After informing Dispatch they got back to us and said with the fuel on board and our FMC reports we should land above flight plan fuel at 5.6 lbs and we were fine. Our REV was 3.33; and planning on landing with 5.6 so from my experience it's easy to land below what the flight plan has planned at distention but not this low. There was a possibility that we could even land at a lower number than 3.1 now showing with radar vectoring etc. because this was still early in the flight.  I recommended to the captain that we should divert as this would be the safest course of action because there was a possibility that the aircraft was burning more fuel than planned and this 3.2-3.1 could be a real number eating into our reserve. After captain agreed we diverted and landed; at the gate with 5.6LB. Maintenance found a popped circuit breaker to the number 2 engine control which could have effected its burn.
We elected to make a fuel stop then continue to destination. We landed with 5.5. This was confirmed with having the fuel tanks dripped and by calculating fuel used from gate fuel. Upon landing; maintenance noticed the number 2 engine control circuit breaker was out. Circuit breakers were all checked in during preflight by both pilots.
B737 flight crew reported departing with the correct fuel load on board then discovering enroute that they would be landing with significantly less fuel than planned. The crew elected to divert for fuel and Maintenance found a fuel control circuit breaker tripped; but no direct cause for the excessive fuel consumption.