Narrative:

The cockpit fuel gauges showed the required fuel load for our flight during our pre-departure setup. Approximately 2 hours into the flight; the fuel tanks abruptly showed an imbalance in exceedance of the maximum amount. A cross feed of fuel was made to bring the tanks back into balance. It was about this time that our FMC fuel began to show that we were below the amount required for our point in time of the flight. We notified line maintenance of the problem and began doing a series of checks related to fuel burned and noticed nothing unusual. Our total fuel for arrival into ZZZ was beginning to show a steady trend of depletion so that when it reached the point that the FMC was showing us with an arrival fuel of 3700 lbs. (Approximately far minimums); we decided to land at ZZZ1 which at that time was about 80 NM ahead of us. The gauges on final approach at ZZZ1 were showing a total of 6000 lbs. And balanced but after landing during taxi in they jumped up to a total of 7200 lbs. And showed an out of limits balance again. Upon a thorough maintenance inspection by [company] mechanics who were brought in from ZZZ overnight; we were told that we actually had 3400 lbs. Of fuel on board at shutdown in ZZZ1.needless to say; had we continued on to ZZZ; it would have probably not been a good ending. The right quantity indicator was deferred inop; fuel was metered on by the truck and we ferried the aircraft to ZZZ the next morning. It is my opinion that the improper fuel was loaded and no cross checks were done to ensure that the gauges were in fact functioning properly.

Google
 

Original NASA ASRS Text

Title: B737 flight crew reported inaccurate fuel indication led to a diversion.

Narrative: The cockpit fuel gauges showed the required fuel load for our flight during our pre-departure setup. Approximately 2 hours into the flight; the fuel tanks abruptly showed an imbalance in exceedance of the maximum amount. A cross feed of fuel was made to bring the tanks back into balance. It was about this time that our FMC fuel began to show that we were below the amount required for our point in time of the flight. We notified Line Maintenance of the problem and began doing a series of checks related to fuel burned and noticed nothing unusual. Our total fuel for arrival into ZZZ was beginning to show a steady trend of depletion so that when it reached the point that the FMC was showing us with an arrival fuel of 3700 lbs. (approximately FAR minimums); we decided to land at ZZZ1 which at that time was about 80 NM ahead of us. The gauges on final approach at ZZZ1 were showing a total of 6000 lbs. and balanced but after landing during taxi in they jumped up to a total of 7200 lbs. and showed an out of limits balance again. Upon a thorough maintenance inspection by [Company] mechanics who were brought in from ZZZ overnight; we were told that we actually had 3400 lbs. of fuel on board at shutdown in ZZZ1.Needless to say; had we continued on to ZZZ; it would have probably not been a good ending. The right quantity indicator was deferred inop; fuel was metered on by the truck and we ferried the aircraft to ZZZ the next morning. It is my opinion that the improper fuel was loaded and no cross checks were done to ensure that the gauges were in fact functioning properly.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.