I picked up the idea from the Eggenfellner Subaru group.  They had had a couple of instances where pilots ran one tank dry and then couldn’t get the EFI pump to re-prime, and ended up in off-field landings.  It is now a mandatory change for anyone running the Eggenfellner package

 

Before installing the bypass bleeder circuit, it would not re-prime unless I cracked open a line downstream of the pump. 

 

Mark S.

 

I’m not sure I get this.  It must be system design dependant.  I have filled my tanks from dead empty; turned on the pump and immediately had fuel pressure.  Ran the tanks dry; then added some fuel; turned on the pump – immediately had pressure.  True; I have done this on the ground, but should it be any different in the air.  The key may be that the line from my sump tank to the pump has a slight downward slope so the fuel will fill the line and the air goes back to the sump.

 

What does the .025 bypass orifice do that open injectors while engine cranking won’t do?

 

Al

 

That's the problem with this kind of data.  I'm sure the Eggenfellner people were telling the truth about what they saw but you can't then generalize and make their solution a 'carved-in-stone' rule.  I have no details on their system but I suspect there was a deficiency in their fuel system which their bleeder fix covered up or compensated for.    Like Al, I've never seen this problem on my plane or engine test stand.

 

Tracy  (trying to figure out why I can't change the text color when I reply to Al's posts)