A DC9-30 AT FL350 NOTED FUEL IMBAL OF 1200 LBS. ADVISED DISPATCH. DIVERTED DUE TO SUSPECTED FUEL LEAK. ON GND R TANK QUANTITY INCREASED.

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NOTICED FUEL IMBAL OF 1200 LBS BTWN THE L MAIN AND THE R MAIN TANK 40 NM E OF ZZZ. OPEN XFEED TO CORRECT FUEL IMBAL. THAT SEEM TO CORRECT THE FUEL IMBAL. OVER ZZZ CHK THE FUEL REMAINING; WE HAD 8.5 AND THE FLT PLAN SAID WE SHOULD HAVE 10.2. WHEN WE WERE ABOUT 40-50 NM W OF ZZZ NOTICED THAT FOB WAS 8.0 DECREASING FASTER THAN NORMAL. WE CHKED FUEL BURNED AND FUEL TOTAL REMAINING WE WERE COMING UP 2000 LBS SHORT. AT THIS POINT WE RAN THE COM PROC 2.28.9 FUEL LEAK PROC. WE THOUGHT IT WAS MORE APPROPRIATE THAN THE 2.28.14 BECAUSE ALL FUEL QUANTITY INDICATORS APPEARED NORMAL. CALL DISPATCH AND EXPLAINED THE PROB AND TOLD HIM I THOUGHT WE SHOULD DIVERT TO ZZZ BECAUSE OUR FOB WAS INDICATING 6.8 AND COULD NOT DETERMINE THE SOURCE OF THE LEAK OR FUEL LOST. BOTH FUEL TANKS L AND R WERE INDICATING APPROX THE SAME QUANTITY 3.4/3.6. WE DIVERT TO ZZZ AND LANDED WITH ABOUT 6.8 FOB. WE NOTICED THAT FUEL TOTAL REMAINED PRETTY CONSTANT WHILE DIVERTING TO ZZZ. AT THE GATE WHEN SHUT THE ENGS DOWN FUEL REMAINING WAS L MAIN 3.2 AND R MAIN WAS 3.6. ABOUT 1 1/2 HR LATER; WHILE WAITING AT THE QUANTITY IN THE R MAIN WAS READY 4.180 AND THE L WAS 3.180 FOB OR TOTAL FOB OF 7.3; 500 LBS MORE THAN WE LANDED WITH. BUT STILL COULD NOT ACCOUNT FOR THE LARGE DIFFERENCE IN FUEL. THE LONGER I HUNG AROUND ZZZ AND TALKING TO MAINT CTLR; I SUSPECT THAT MAYBE THE R FUEL QUANTITY INDICATOR IS ERRONEOUS. BUT AT THE TIME WE DIVERTED TO ZZZ WE THOUGHT WE HAD A FUEL LEAK. ON AUG/SUN/04; CALL MAINT CTL; AND WAS ADVISED THE R FUEL QUANTITY INDICATOR WAS BAD. AUG/WED/04; THE R FUEL QUANTITY INDICATOR WAS WRITTEN UP AS ERRONEOUS; MAINT DID A BYTE TEST ON THE DIGITAL INDICATORS/CHK NORMAL/REPLACE R FUEL QUANTITY INDICATOR AT ZZZ.