In flight today I experimented with "high" boost switch position. It adds about 4-5 gph to the fuel flow-- and miraculously the engine did not quit! So, for all those folks feverishly redesigning the TCM fuel system -- relax and take a few deep breaths and have another beer.

Jeff,

 

Fabulous!  On my Lyc IO system, If I add the boost pump it raises the pressure 1-2 psi above the engine pump standard (25-26 psi) - there is no change in the fuel flow unless the low pressure light comes on (<12 psi, fluctuating fuel flow, no smiley faces on the annunciators) and the engine pump is cavitating from having the vapors. 

 

There is no return line, thus hot starts require being at one with the engine (yes, machines are affected by transcendental meditation and atonal chants using syllable subsets from $&^@^&%&^$). 

 

I am proud that my pressure relief regulator is doing its job in its own secret way.

 

Grayhawk