Today's Message Index:
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1. 05:49 AM - Re: Re: Auto Aux Fuel Pump Circuit Idea (Glen Matejcek)
2. 08:02 AM - Re: Re: Re: Auto Aux Fuel Pump Circuit Idea (Ken)
3. 02:15 PM - Re: Re: Re: Auto Aux Fuel Pump Circuit Idea (Kenneth Johnson)
4. 10:13 PM - Matronics Web Services Restored! (Matt Dralle)
Message 1
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Subject: | Re: Re: Auto Aux Fuel Pump Circuit Idea |
Hi All-
I may have missed something in the exchanges here, but I think a couple data points
might have been overlooked. First, one of the differences in the aircraft
and automotive fuel systems is that the automotive system works at ground level.
The aircraft system needs to work at lower ambient atmoshpheric pressures,
and is therefore inherently more vapor lock prone than an automotive system
with the same fuel at the same temperature.
Another data point is that when the automotive, tank mounted pump fails, you coast
over to the side of the road. It's a little more complicated when the pump
in a pump dependent aircraft fuel system quits.
A a reminder, the common philosophy behind aircraft boost pumps is to provide fuel
pressure when the engine driven pump can't, I.E. for priming or when the EDP
has failed. If an aircraft fuel system has turned out to need the boost pump
in order to operate safely under nominal circumstances, I would suggest that
there is another problem that needs to be addressed and that using the boost
pump is a band aid, not a solution.
The last thing is that the plans for my fuel injected RV called for quite a bit
of seemingly unnecessary tubing in the return line back to the selector valve.
Turns out that the whole point there is to provide a radiator. If one were
to get creative and shorten that line, the system would end up more vapor lock
prone.
FWIW, YMMV, ETC
Glen Matejcek
Message 2
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Subject: | Re: Re: Auto Aux Fuel Pump Circuit Idea |
> The last thing is that the plans for my fuel injected RV called for
> quite a bit of seemingly unnecessary tubing in the return line back
> to the selector valve. Turns out that the whole point there is to
> provide a radiator. If one were to get creative and shorten that
> line, the system would end up more vapor lock prone.
>
Actually after watching attempts to cool and reintroduce bypassed fuel
into the pump end in bent airplanes, most folks agree that the issue is
venting the vapour bubbles back to a tank or header. Merely cooling
doesn 't cut it for automotive EFI installations. Maybe it works better
with 100LL. When the pressure drops at the regulator there is excellent
conditions to create vapour bubbles, some of which are air and not all
of which will readily re-condense.
Ken
Message 3
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Subject: | Re: Re: Auto Aux Fuel Pump Circuit Idea |
Hi All,=0AI seldom write because I am far from an expert in this area.- I
n addition I have not finished building my plane.- However, I will offer
this suggestion as it has been recommended for my engine.- I am using a M
azda rotary engine.- This automotive engine has a fuel rail with a return
fuel line to my main fuel tank.- With the engine, a MSD Ignition high pr
essure electric fuel pump (Part # 2225) was included.- Because this is a
very important part for engine function, a second pump has been plumbed in
parallel with check valves for each.- There are separate switches for eac
h, which allows one to use either one.- I am uncertain about using them b
oth together, as I am not that far, or if would even be necessary.- These
fuel pumps have been placed on the pilots side of the firewall and the fue
l is pumped about 2 feet to the fuel rail. - I have looked up information
regarding this fuel pump and it appears to be reliable and that is why I h
ave
written.- If others have experience with this fuel pump, it would be ope
n for discussion.- =0A=0AKen Johnson=0A=0A=0A=0A_________________________
_______=0A From: Glen Matejcek <aerobubba@earthlink.net>=0ATo: aeroelectric
-list@matronics.com =0ASent: Wednesday, December 7, 2011 7:45 AM=0ASubject:
AeroElectric-List: Re: Re: Auto Aux Fuel Pump Circuit Idea=0A =0A--> AeroE
lectric-List message posted by: Glen Matejcek <aerobubba@earthlink.net>=0A
=0AHi All-=0A=0AI may have missed something in the exchanges here, but I th
ink a couple data points might have been overlooked.- First, one of the d
ifferences in the aircraft and automotive fuel systems is that the automoti
ve system works at ground level.- The aircraft system needs to work at lo
wer ambient atmoshpheric pressures, and is therefore inherently more vapor
lock prone than an automotive system with the same fuel at the same tempera
ture.=0A=0AAnother data point is that when the automotive, tank mounted pum
p fails, you coast over to the side of the road.- It's a little more comp
licated when the pump in a pump dependent aircraft fuel system quits.=0A=0A
A a reminder, the common philosophy behind aircraft boost pumps is to provi
de fuel pressure when the engine driven pump can't, I.E. for priming or whe
n the EDP has failed.- If an aircraft fuel system has turned out to need
the boost pump in order to operate safely under nominal circumstances, I wo
uld suggest that there is another problem that needs to be addressed and th
at using the boost pump is a band aid, not a solution.=0A=0AThe last thing
is that the plans for my fuel injected RV called for quite a bit of seeming
ly unnecessary tubing in the return line back to the selector valve.- Tur
ns out that the whole point there is to provide a radiator.- If one were
to get creative and shorten that line, the system would end up more vapor l
=========================0A
===================
Message 4
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Subject: | Matronics Web Services Restored! |
Dear Listers,
I'm extremely happy to report that as of about 9pm PST 12/7, all of the Matronics
web services have been fully restored including the Web Forums, List Browse,
Archive Search, Wiki, and AeroElectric web sites. It was quite an ordeal getting
the replacement boards for the server, but things went back together tonight
and are up and running nicely. The first company I ordered the boards from
originally called me a day later to say that, whoops, they really didn't have
them in stock after all... Fortunately, I was able to locate some through
a different source and had then over-nighted and they arrived today.
Thank you for your patience and consideration though the whole thing!
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