I will share again my experience with numerous burps (vaporization) in the fuel when switching tanks the first time at flight levels FL200-250).  It was worse on hot days.

 

Cure:  I moved the fuel pump off the side wall to the floor on the copilot side between the wheel well and the exhaust tunnel.  I have had only one hesitation of the engine since moving the pump. 

 

Conclusion:   Mount the fuel pump where it always pumps—on the floor somewhere.

 

 We operate very close the vapor point of the fuel at high altitudes.  If we don’t suck on the fuel we don’t lower the partial pressure any further.  Now the pump operates as a pump as the level is below the fuel level in a full wing.

 

Carl Cadwell

N25CL, IVP 425 hrs.