<... Do you suppose that this wouldn’t react fast enough to keep the engine running? ...>
Even if you didn't have the automatic switchover, I bet YOU would react fast enough so the prop would never stop.  What I wonder about is with auto changeover, how do you know the primary pump failed?  And how would you be able to shut down the engine by turning off the pump?  I assume that if the auto changeover fails, you can still turn on the backup manually.
Just wonderin'  .... Jim S.
 

Al Gietzen wrote:

Perry wrote:

If you are flying and running only one h.p. fuel pump, and that pump fails, the engine will become silent only milliseconds later! 

This is interesting.  As my circuit diagram is currently configured, I have a pressure switch in the fuel system which automatically turns on the backup pump if the pressure drops below about 30 psi. (don’t remember now the exact setting on the pressure switch).  Do you suppose that this wouldn’t react fast enough to keep the engine running?

  There is a manual bypass so I can turn the pump on if I want.  The idea was to turn on both pumps for takeoff, but at other times the backup would automatically kick in to keep the engine from stopping if the primary pump stopped; thereby avoiding rapid heart rates on the part of pilot and passengers.