What was found
AT L/O , FL 360 GOT LVL 1 ALERT FOR " TNK 3 TIP TRAPPED" WITH APPX 8.0 K FUEL IN #3, MEANING WE ONLY HAD 8.0 - 5.8 = 2.2 IN NR 3 TANK , AND INSUFFICIENT FUEL TO MAKE DESTINATION , ALERT WENT AWAY AFTER 2 MIN BUT ON DESCENT, GOT TNK 3 FUEL QTY LO ALERT WITH 6.1 IN TNK 3. QRH SAYS INBD CMPTMT FUEL IS LESS THAN 3.5 K W/ABOUT 100 MILES TO GO DECLARED EMERGENCY AND LANDED, BLOCKED IN WITH 5.8 K IN NR 2. WHILE COMPLYING WITH TSI 28-41 7551 STEP 2 INSPECTION OF GRAVITY TRANSFER SYSTEM TUBING, FOUND BROKEN PRESSURE SENSE LINE ON TRANSFER FLOAT VALVE. REMOVED AND REPLACED TRANSFER FLOAT VALVE PRESSURE SENSE LINE IAW AMM 28-21-10-2. OPS CHECKED GOOD IAW FIM 28-14-00-2, TASK 28-14-00-810-803. ACFT OK FOR SERVICE.