Also the QRH doesn't mention a popped circuit breaker in the crossfeedvalve inoperable procedure. If both bulbs in a light are burned out in less than an hour after preflight checks then it's probably not the bulbs. I should have scanned for popped circuit breakers and referenced the QRH more quickly. The aircraft was taken out of service and the passengers and crew continued to the scheduled destination on another aircraft that arrived shortly after we deplaned. Operations had a gate ready for us and maintenance was at the aircraft just a few minutes after we arrived. We landed under max landing weight and the fuel imbalance was 900 pounds. The approach and landing were uneventful. I used the right center tank pump to fuel depletion to minimize the fuel imbalance.
I informed the flight attendants of our decision to divert and then made a PA to let the passengers know we'd be diverting. I coordinated with dispatch and the first officer coordinated with ATC. I chose hub because of maintenance and passenger accommodation capabilities. We were about 160 miles southeast of a major hub and about 80 miles from an out station. I felt uncomfortable securing the left fuel pumps to maintain the fuel balance because of the possibility of the loss of adequate fuel pressure to the left engine. With fuel being consumed unequally from both tanks and no crossfeed valve position light I could not confidently determine the position of the crossfeed valve. The fuel flow on the engines was almost identical. In the span of about twenty minutes the right quantity decreased by about 1 300 pounds and the left decreased by about 400 pounds. We initially had a fuel imbalance of about 200 pounds greater in the right wing. I secured the center tank pumps with 850 pounds remaining in the center tank. The first officer and I reviewed QRH fuel balancing methods and discussed diverting if we could not maintain the fuel balance. Both center tank fuel pumps were on while we were evaluating our situation so I decided to continue using both center tank pumps for a few more minutes until the center fuel tank quantity was just below one thousand pounds. I began a fuel burn log to see if we could determine what was being burned where and possibly determine the position of the crossfeed valve. We discussed the procedure noting that it did not match our situation exactly because we could not use the valve position light to determine the position of the crossfeed valve. The first officer referenced the QRH and turned to the crossfeed valve inoperable procedure. We did not reset the circuit breaker a second time. It appeared that the crossfeed valve position light would not test or operate with the crossfeed valve circuit breaker open. We found the crossfeed valve circuit breaker was open again. The position indicator light briefly illuminated and then went out. I again attempted to open the crossfeed valve. After discussing the situation with the first officer I reset the circuit breaker the valve position light properly illuminated during the press to test and when using the light test switch. I scanned the circuit breaker panel and found the crossfeed valve circuit breaker open. The valve position light was still inoperable. I changed both bulbs and checked the light by pressing to test and by using the light test switch. I was surprised that both bulbs in the light would have burned out in the short period since successful preflight checks. The light failed to illuminate during both tests so I assumed the bulbs were out.
I checked the valve position light bulbs by pushing on the light and by using the light test switch. The crossfeed valve position indicator light failed to illuminate when I opened the crossfeed valve. During cruise flight with approximately two thousand pounds of fuel remaining in the center tank I attempted to open the crossfeed valve and use the one center tank pump to burn the remaining fuel in that tank.
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