Narrative:

I am the captain and was the pilot monitoring for the flight. We were delayed about 2 hours due to late arriving aircraft. There was some sense of time pressure; which was self-imposed; to get the flight out. I was dealing with a maintenance issue and requirements to contact dispatch. During the before engine start checklist I only turned on one center tank pump with fuel in the center tank. The pump I turned on was the left one. Due to aircraft design there are no pressure lights when one center pump is on and one is left off. After takeoff and during the 10000 foot check on the after takeoff climb check I noticed that the right main tank fuel was decreasing when fuel feed should have been from the center. I was flying away from airport ZZZ and going towards the mountains. As we continued to climb the right main continued to decrease. I looked at the fuel panel and did not see any lights. I got concerned that we were going away from airport ZZZ and towards the mountain and appeared to have a fuel leak. I wanted to stay closer to airport ZZZ while I tried to figure out the problem so I declared an emergency and asked for a turn back towards airport ZZZ. While in the turn I noticed that the right center fuel pump was off. I turned it on and this resolved the abnormal fuel feed situation. I told departure that I was terminating the emergency and wanted to turn back on course. We basically did a 360 turn and then continued. Fuel feed was normal from this point on. We landed with normal burn. I did not feel like we were overly rushing to get out of airport ZZZ but I obviously missed the center fuel pump during the before start engine checklist. I tend to do a scan of the overhead panel just prior to takeoff but it is more of a light check than a switch check. I will modify my scan to include switch positions. When I first noticed the imbalance I was torn between giving some time and continuing on to trouble shoot and staying close to airport ZZZ. The imbalance was occurring rapidly so prior to doing any abnormal checklist I decided to turn back towards airport ZZZ instead of going over the mountains. Once again I am sure I looked at the fuel panel but most likely only for lights and not switch positions. During the turn I finally noticed the switch. Two major lessons:1. Never rush (sometimes difficult to due)2. When faced with an abnormal try to wind the clock for a second and think about the most likely causes of the problem.

Google
 

Original NASA ASRS Text

Title: While preparing for the before start checklist; a B737 Captain reports only turning on one center tank fuel pump. This is not detected by either pilot during the checklist and the flight departs in that condition. An impending fuel imbalance is detected during climb and several minutes pass before the cause is detected and corrected.

Narrative: I am the Captain and was the pilot monitoring for the flight. We were delayed about 2 hours due to late arriving aircraft. There was some sense of time pressure; which was self-imposed; to get the flight out. I was dealing with a maintenance issue and requirements to contact dispatch. During the before engine start checklist I only turned on one center tank pump with fuel in the center tank. The pump I turned on was the left one. Due to aircraft design there are no pressure lights when one center pump is on and one is left off. After takeoff and during the 10000 foot check on the after takeoff climb check I noticed that the right main tank fuel was decreasing when fuel feed should have been from the center. I was flying away from Airport ZZZ and going towards the mountains. As we continued to climb the right main continued to decrease. I looked at the fuel panel and did not see any lights. I got concerned that we were going away from Airport ZZZ and towards the mountain and appeared to have a fuel leak. I wanted to stay closer to Airport ZZZ while I tried to figure out the problem so I declared an emergency and asked for a turn back towards Airport ZZZ. While in the turn I noticed that the right center fuel pump was off. I turned it on and this resolved the abnormal fuel feed situation. I told departure that I was terminating the emergency and wanted to turn back on course. We basically did a 360 turn and then continued. Fuel feed was normal from this point on. We landed with normal burn. I did not feel like we were overly rushing to get out of Airport ZZZ but I obviously missed the center fuel pump during the before start engine checklist. I tend to do a scan of the overhead panel just prior to takeoff but it is more of a light check than a switch check. I will modify my scan to include switch positions. When I first noticed the imbalance I was torn between giving some time and continuing on to trouble shoot and staying close to Airport ZZZ. The imbalance was occurring rapidly so prior to doing any abnormal checklist I decided to turn back towards Airport ZZZ instead of going over the mountains. Once again I am sure I looked at the fuel panel but most likely only for lights and not switch positions. During the turn I finally noticed the switch. Two major lessons:1. Never rush (sometimes difficult to due)2. When faced with an abnormal try to wind the clock for a second and think about the most likely causes of the problem.

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.