X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from relay2.mail.twtelecom.net ([216.54.204.190] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTP id 1003542 for flyrotary@lancaironline.net; Wed, 15 Jun 2005 18:48:22 -0400 Received-SPF: neutral receiver=logan.com; client-ip=216.54.204.190; envelope-from=hsanders@bellsouth.net Received: from herbhehbdwmte2 (66-162-168-98.gen.twtelecom.net [66.162.168.98]) by relay2.mail.twtelecom.net (Postfix) with ESMTP id 351D2C354 for ; Wed, 15 Jun 2005 17:47:34 -0500 (CDT) From: "Herb Sanders" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: EFI Bleeder Circuit (Was Engine Not Starting) Date: Wed, 15 Jun 2005 17:47:29 -0500 Message-ID: <000001c571fc$366abfb0$1900a8c0@herbhehbdwmte2> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C571D2.4D94B7B0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C571D2.4D94B7B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Al, a short version of that would be "always design your fuel system so = that gravity flow covers the inlet to your delivery pump naturally". Its = called flooded suction design. Herb =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of al p wick Sent: Wednesday, June 15, 2005 5:08 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: EFI Bleeder Circuit (Was Engine Not Starting) =20 I threw this together, it includes some assumptions, but I think it's = pretty close to reality. I strongly suspect that the Egg fuel bleed system = actually drops the outlet pressure enough that the pump is able to move the small bubble of air at the pump inlet. If you have a well designed system, = that air is displaced automatically and there is no value to the bleed = system. I tested my plane and it definitely self primes. The Egg crash plane would = not pump fuel hours after the vapor lock. It was not a self priming fuel = design. Back to lurking, this my quota of posts for week. ;-) =20 -al wick =20 =20 Subject:=20 Fuel system validation..self priming pump. =20 Scope: This procedure is utilized to determine if your fuel system is able to = self prime. It applies to EFI high pressure fuel systems. =20 General: Self priming fuel systems are lower risk that those that don't. These systems have the ability to resume pumping immediately after a flow interruption. Such as when the pilot runs one tank dry, or if there is = vapor lock. All systems that allow the fuel pump inlet to get wet after a flow interruption are self priming. This condition is vital on high pressure = fuel systems, as the pumps are unable to displace air due to the high = pressure on the outlet side of the pump. Only when the inlet is wet are the pumps = able to resume flow. =20 Procedure: =20 Drain all fuel from your tank. Verify your engine fuel pressure is at normal pressure, this is = typically 36 psi for EFI systems. Activate fuel pump for a few moments to purge fuel from the fuel inlet. = You should hear a rattling sound when inlet is purged of fuel. Use care, = running pump dry too long can damage pump. Add fuel to tank. Activate fuel pump for a few moments until normal pressure is achieved. =20 Conclusion: =20 If unable to achieve full pressure in 10 seconds, you have failed the = test. Modify your fuel system to self wet the fuel inlet. =20 =20 =20 =20 =20 =20 On Wed, 15 Jun 2005 09:13:12 -0500 "Mark R Steitle" writes: > Jofar, > The real purpose of the bleed circuit is to allow the pump to=20 > reprime > itself. Once that happens, the pump builds up pressure again, and > forces all the remaining air out through the pressure regulator. =20 > With a > 5-gal tank sitting on the floor, my system (running one pump) can > reprime itself in about 10 seconds. Yes, under the right=20 > circumstances, > that could be the longest 10 seconds of my life. This should only > happen if you run a tank dry. But if that happens, the procedure=20 > will > be to switch to the other tank (should have fuel), then turn on the > boost pump. That should reduce the recovery time to something less=20 > than > 10 seconds. >=20 > Mark >=20 > -----Original Message----- > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]=20 > On > Behalf Of jesse farr > Sent: Wednesday, June 15, 2005 8:47 AM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Engine Not Starting >=20 > I don't know nothing (actually pretty much anything) about any of=20 > this > but=20 > that has never stopped me from having and voicing an opinion; so, if=20 >=20 > injectors only fire small percentage of time and fuel & compressed=20 > air > flow=20 > not sufficient at times to clear out in time to get started while=20 > flying > ac,=20 > bleed return definitly sounds like good idea. But, if sufficiently=20 > far > away=20 > from injectors, then even though now have flow established to the=20 > bleed=20 > point, you will still have slow go to purge remaining compressed=20 > air, > vapor=20 > and allow fuel to actually flow from there to injectors and inject.=20 > It > may=20 > just take a few seconds longer but that is still a tight a-- time=20 > of > flying,=20 > starting, praying, cursing own stupidity, etc.. Could I suggest=20 > might be >=20 > better to put bleed point at end of fuel rail so as to pass vapor=20 > all > the=20 > way more quickly ? After all, small orfice and line return to tank > shouldn't=20 > create that much more of a problem. Is there some other problem=20 > there > that I=20 > simply do not know enough to understand ? > jofarr, soddy tn >=20 > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html >=20 >=20 =20 =20 -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ------=_NextPart_000_0001_01C571D2.4D94B7B0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Al, a short version of that would = be “always design your fuel system so that gravity flow covers the inlet to your = delivery pump naturally”.   Its called flooded suction = design.  Herb

 

-----Original Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of al p wick
Sent: Wednesday, June 15, = 2005 5:08 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: = EFI Bleeder Circuit (Was Engine Not Starting)

 

I threw this together, it includes some assumptions, but I think = it's pretty close to reality. I strongly suspect that the Egg fuel bleed = system actually drops the outlet pressure enough that the pump is able to move = the small bubble of air at the pump inlet. If you have a well designed = system, that air is displaced automatically and there is no value to the bleed = system. I tested my plane and it definitely self primes. The Egg crash plane would = not pump fuel hours after the vapor lock. It was not a self priming fuel = design.

Back to lurking, this my quota of posts for week. = ;-)

 

-al wick

 

 

Subject:

Fuel system validation….self priming = pump.

 

Scope:

This procedure is utilized to determine if your fuel system is = able to self prime. It applies to EFI high pressure fuel = systems.

 

General:

Self priming fuel systems are lower risk that those that don't. = These systems have the ability to resume pumping  immediately after a = flow interruption. Such as when the pilot runs one tank dry, or if there is = vapor lock.

All systems that allow the fuel pump inlet to get wet after a = flow interruption are self priming. This condition is vital on high pressure = fuel systems, as the pumps are unable to displace air due to the high = pressure on the outlet side of the pump. Only when the inlet is wet are the pumps = able to resume flow.

 

Procedure:

 

Drain all fuel from your tank.

Verify your engine fuel pressure is at normal pressure, this is typically 36 psi for EFI systems.

Activate fuel pump for a few moments to purge fuel from the fuel = inlet. You should hear a rattling sound when inlet is purged of fuel. Use care, running pump dry too long can damage pump.

Add fuel to tank.

Activate fuel pump for a few moments until normal pressure is = achieved.

 

Conclusion:

 

If unable to achieve full pressure in 10 seconds, you have = failed the test. Modify your fuel system to self wet the fuel = inlet.

 

 

 

 

 

 

On Wed, 15 Jun 2005 09:13:12 -0500 "Mark R Steitle" = <mark.steitle@austin.utexas= .edu> writes:
> Jofar,
> The real purpose of the bleed circuit is to allow the pump to
> reprime
> itself.  Once that happens, the pump builds up pressure again, = and
> forces all the remaining air out through the pressure = regulator. 
> With a
> 5-gal tank sitting on the floor, my system (running one pump) = can
> reprime itself in about 10 seconds.  Yes, under the right
> circumstances,
> that could be the longest 10 seconds of my life.  This should = only
> happen if you run a tank dry.  But if that happens, the = procedure
> will
> be to switch to the other tank (should have fuel), then turn on = the
> boost pump.  That should reduce the recovery time to something = less
> than
> 10 seconds.
>
> Mark
>
> -----Original Message-----
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironlin= e.net]
> On
> Behalf Of jesse farr
> Sent: Wednesday, June 15, 2005 8:47 AM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: Engine Not Starting
>
> I don't know nothing (actually pretty much anything) about any of =
> this
> but
> that has never stopped me from having and voicing an opinion; so, = if
>
> injectors only fire small percentage of time and fuel & = compressed
> air
> flow
> not sufficient at times to clear out in time to get started while =
> flying
> ac,
> bleed return definitly sounds like good idea. But, if sufficiently =
> far
> away
> from injectors, then even though now have flow established to the =
> bleed
> point, you will still have slow go to purge remaining compressed =
> air,
> vapor
> and allow fuel to actually flow from there to injectors and inject. =
> It
> may
> just take a few seconds longer but that is still a tight a-- time =
> of
> flying,
> starting, praying, cursing own stupidity, etc.. Could I suggest =
> might be
>
> better to put bleed point at end of fuel rail so as to pass vapor =
> all
> the
> way more quickly ? After all, small orfice and line return to = tank
> shouldn't
> create that much more of a problem. Is there some other problem =
> there
> that I
> simply do not know enough to understand ?
> jofarr, soddy tn
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancai= ronline.net/lists/flyrotary/List.html
>
>

 

 

-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru = 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design = info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html

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