"Barnyard BOb --" wrote in message
...

GRAVITY... and only GRAVITY.
No mechanical engine driven or electric boost pump
No fuel pressure gage, either

You're dead nuts on about 'restrictions'....
hampering a gravity only system.

I dare NOT install an electric pump directly in the line.
Van's sez it's OK to do that with an RV3 gravity system,
but I doubt if they have ever tried it for themselves. The
check valve restriction through the electric pump
combined with the puny 14 inch or so head is asking
for HUGE troubles with the boost pump off or failed, IMO.
At least with a half tank of fuel and high AOA, like...
at take-off trying to feed 60-80 of the 150 hungry horses?
[Remember we are only spinning at 2200 rpm, not 2700.]

What I have in mind is a PARALLEL path for an electric
boost pump...PREFERABLY without a check valve in
the system.

Think I can get away without one? ---
Think CAREFULLY, before you answer.


Barnyard BOb -- engage brain before putting mouth into gear

I have been mulling over several different questions regarding fuel system
plumbing in the last year or so - even up to the last resort of an extra one
gallon (or so) tank with a mechanical pump piped to the intake manifold
after the carb.

As for your concept, I think it would require a shutoff valve to keep the
electric pump from pumping in a circle. Unless the electric pump had
sufficient flow to create friction loss in the line leading back to the
tank, that is. I'd have to get out my tables for friction loss to figger
that one out. Used to be able to do it in my head with a fire engine roaring
next to me.

How about a solenoid operated valve tied to the electric pump switch?

Rich S.