ACR TAKES OFF OVERWT DUE FUELING PROBLEM.

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POSSIBLE OVERWT TKOF DURING PREFLT JUST AFTER REFUELING WE NOTICED A DISCREPANCY BTWN FUEL BOARDED FUEL ON BOARD; AND FUEL QUANTITY TOTAL. FUEL SLIP SAID 106400 POUNDS. GAUGES READ 107100 BUT TANKS ONLY HOLD 105.8. LEFT FUEL GAUGE IA READ 8400 POUNDS. THIS IS NOT POSSIBLE (7900 AT THE MOST). REQUIRED FUEL FOR FLT WAS 105.3 MINUS TAXI EQUALS 103.9. SO I ASSUMED THAT WE HAD FULL FUEL LOAD OF 105800 POUNDS. WE WERE READY FOR PUSH SO I DIDN'T WANT TO DELAY FLT TO HAVE MAINT STICK THE TANKS. JUST BEFORE PUSH LOAD PLANNER TOLD US WE WERE 394 POUNDS OVER GROSS SO WE TOLD HIM WE WOULD BURN OFF FUEL BEFORE TKOF. BASED ON OUR OWN CALCULATIONS WE NEEDED TO BURN OFF ABOUT 2300 POUNDS (1400 TAXI PLUS 900) AN ADDITIONAL 500 POUNDS MORE THAN THE LOAD PLANNER HAD SAID AND TKOF WITH 103.4 POUNDS SO WE DID. LATER IN FLT I WAS READING MY FLT MANUAL AND FOUND OUT THAT BY FUELING WITH HIGH LEVEL SENSOR CUT OFF SWITCHES YOU CAN GET A TOTAL OF 109.7 POUNDS ON THE ACFT; SO IT IS POSSIBLE THAT THESE SENSOR SWITCHES MALFUNCTIONED AND WE DID END UP WITH 106.4 TO 107.1 POUNDS OF FUEL WHICH MEANS WE WERE OVER GROSS AT TKOF. I HAVE OFTEN SEEN THESE GAUGES READ HIGHER THAN NORMAL BUT NOT AS HIGH AS THIS TIME. I SHOULD HAVE TAKEN THE DELAY AND HAD MAINT CHK THE FUEL ON BOARD AND I SHOULD READ MY FLT MANUAL MORE OFTEN.