Yvon Cournoyer wrote:


Good morning,
I have modified my fuel system by adding a second in-line

fuel pump in parallel with the first pump. I also added a one
way valve after each pump and installed one single filter
after the one way valves. This adds up to many connections in
the fuel lines. After testing and flying this system I find
that it works well, but takes up a lot of space.

Are the one way valves necessary with in line cylindrical

type EFI fuel pumps? The pressure in my system is set at 15 psi.

By removing the one way valves I could install one filter

per pump and still save space and several connections.

Yvon.

I am not sure about other pumps, but the inline fuel pumps I used (got them
from Tracy) have check valves built in. You could verify whether they have
the valves by observing the system fuel pressure after shut down, if it
bleeds down quickly you have no check valves. On an EFI automobile, the
pressure can stay up for days or weeks after shutdown, so I would assume
most pumps would have the check valve. Only 15 PSI for EFI? most use 40-50
PSI.

Chuck Dunlap

The problem is that if the pump destroys itself it is highly likely that the
internals will be deranged and the pump valves cannot be depended
on to work normally.  We gotta think like Murphy here, guys!

Ya'll be careful out there.

Bill  Freeman

 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org