Doesn't matter what others say -- you should see fuel pressure as required for the specific engine that you are operating.  Apparently the engine fuel pump may not be adequate above 10,000 and most will recommend lo boost pump on above 10K.  Whatever the pressure is, it must meet the engine requirements.

 

Grayhawk

 

What fuel pressures that you are seeing at altitudes from 10 to 15,000 feet with the fuel pump off for a continental io-550?

 

Thanks

Russell Steiner