Narrative:

I filed IFR [for my flight] and planned to go direct. I was cleared direct to my destination and departed. Approximately 3 hours into the flight at 9;000 feet the engine experienced power interruption due to fuel stoppage. In addition to the normal fuel; the 2 wing tanks had 20 gallons each. Fuel management had been in effect for the entire flight. I advised ATC of the problem and changed from the left wing to the right wing without the engine restarting. The propeller was wind milling. I applied the electric fuel pump and the engine came to life. I advised ATC that the engine was running. I prepared to land at [a nearby airport] and asked for tower frequency. I called the tower with the airport in view and advised that I was 5-6 miles west for landing. I was cleared for landing. After landing; I turned off the runway and experienced total engine stoppage due to the electric fuel pump over boosting the engine. The aircraft was towed to FBO. I advised them what had occurred and assumed the engine driven fuel pump had ceased to operate. The mechanics opened the cowling to see if the obvious could be observed. Mechanic advised me he would remove the fuel pump and call me. I rented a car and proceeded to my destination. Later I received a call from [the mechanic] stating he had removed the pump and performed a bench test and not an ounce of fuel came out of the pump. We discussed the fact that a new pump could not be obtained [for a few days]. [The mechanic] called me the following day and he was extremely puzzled after inspecting the pump he found very little wrong with it; with minor exceptions. He had tested the pump with another pump in the shop and there was 15 gallons per hour flow on the test pump and on the pump removed from my aircraft there was only 4 gallons per hour. Both of us concurred it was a bad pump. On the day of departure after all maintenance had been completed; and during the test phase he discovered no fuel in the left wing. This was extremely perplexing. He said he had observed some blue staining on the top of the wing and feared a bladder had ruptured. We examined the fuel cap and it appeared to be functional. The aircraft was totally fueled and [the mechanic] moved the wing back and forth to see if there was fuel seepage. Seeing none; we concluded the cap was sufficient. I then departed. Upon take-off; I noted a tremendous amount of fuel coming from the left wing cap. I notified the tower and returned for landing. [The mechanic] changed both gaskets on each fuel cap and noted the aircraft lost approximately 7 gallons in the short flight. Upon becoming airborne again; we encountered no problem whatsoever. I might add that I contacted two repair shops and inquired what might have caused the pump to fail so quickly. Both thought it was unusual and only an examination of the pump could determine the cause. [The mechanic] said he would send the pump to a facility for examination. Until we find out why the pump did not perform properly on test; we can only conclude the reason for the engine stoppage was lack of fuel caused by seepage of fuel from the left wing or a failed fuel pump or a combination of the two.

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Original NASA ASRS Text

Title: BE33 pilot reported diverting due to a loss of power later traced to either a defective engine fuel pump or a wing tank leak.

Narrative: I filed IFR [for my flight] and planned to go direct. I was cleared direct to my destination and departed. Approximately 3 hours into the flight at 9;000 feet the engine experienced power interruption due to fuel stoppage. In addition to the normal fuel; the 2 wing tanks had 20 gallons each. Fuel management had been in effect for the entire flight. I advised ATC of the problem and changed from the left wing to the right wing without the engine restarting. The propeller was wind milling. I applied the electric fuel pump and the engine came to life. I advised ATC that the engine was running. I prepared to land at [a nearby airport] and asked for Tower frequency. I called the Tower with the airport in view and advised that I was 5-6 miles west for landing. I was cleared for landing. After landing; I turned off the runway and experienced total engine stoppage due to the electric fuel pump over boosting the engine. The aircraft was towed to FBO. I advised them what had occurred and assumed the engine driven fuel pump had ceased to operate. The mechanics opened the cowling to see if the obvious could be observed. Mechanic advised me he would remove the fuel pump and call me. I rented a car and proceeded to my destination. Later I received a call from [the mechanic] stating he had removed the pump and performed a bench test and not an ounce of fuel came out of the pump. We discussed the fact that a new pump could not be obtained [for a few days]. [The mechanic] called me the following day and he was extremely puzzled after inspecting the pump he found very little wrong with it; with minor exceptions. He had tested the pump with another pump in the shop and there was 15 gallons per hour flow on the test pump and on the pump removed from my aircraft there was only 4 gallons per hour. Both of us concurred it was a bad pump. On the day of departure after all maintenance had been completed; and during the test phase he discovered no fuel in the left wing. This was extremely perplexing. He said he had observed some blue staining on the top of the wing and feared a bladder had ruptured. We examined the fuel cap and it appeared to be functional. The aircraft was totally fueled and [the mechanic] moved the wing back and forth to see if there was fuel seepage. Seeing none; we concluded the cap was sufficient. I then departed. Upon take-off; I noted a tremendous amount of fuel coming from the left wing cap. I notified the Tower and returned for landing. [The mechanic] changed both gaskets on each fuel cap and noted the aircraft lost approximately 7 gallons in the short flight. Upon becoming airborne again; we encountered no problem whatsoever. I might add that I contacted two repair shops and inquired what might have caused the pump to fail so quickly. Both thought it was unusual and only an examination of the pump could determine the cause. [The mechanic] said he would send the pump to a facility for examination. Until we find out why the pump did not perform properly on test; we can only conclude the reason for the engine stoppage was lack of fuel caused by seepage of fuel from the left wing or a failed fuel pump or a combination of the two.

Data retrieved from NASA's ASRS site as of July 2013 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.