X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-fx0-f52.google.com ([209.85.161.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTPS id 5095193 for flyrotary@lancaironline.net; Wed, 17 Aug 2011 12:20:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.161.52; envelope-from=msteitle@gmail.com Received: by fxd18 with SMTP id 18so731785fxd.25 for ; Wed, 17 Aug 2011 09:19:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=KTqY9i03W0CX/qYjafyaGonMZX8hy4I5yx4V6e/UHNo=; b=ng1ib9MXp2R8qdlcsXzJgND6Pjl2QsUIs4DvTrkcRS9hMXE/clzxH3Z4HTA+kY+tNE pfJHrgoJVMhXToD4X16N961k5AIACi1EHNrhfvHlMp3ZPoriWV5+2upuek8Z91eJ0P2c /w/AedED7D/43J04cQYRy8arzzlgP4nlpm4O8= MIME-Version: 1.0 Received: by 10.223.96.13 with SMTP id f13mr1664998fan.37.1313597975906; Wed, 17 Aug 2011 09:19:35 -0700 (PDT) Received: by 10.223.74.129 with HTTP; Wed, 17 Aug 2011 09:19:35 -0700 (PDT) In-Reply-To: References: Date: Wed, 17 Aug 2011 11:19:35 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Dennis Haverlah Fuel System...or any others, for that matter. From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=20cf3054ad49bb4bbf04aab5dca1 --20cf3054ad49bb4bbf04aab5dca1 Content-Type: text/plain; charset=ISO-8859-1 Al, I would think that a well-designed fuel system with the pumps located as low as possible, in a cool area, and a return system should not be troubled with vapor locking. Although I guess it could happen in Death Valley in August if the a/c is left out in the sun for 8 hours, and running auto gas. So far, I haven't had any problem here in Texas (temps 105* today). My purpose for installing the bypass circuit was more critical to safe flight. (The solution was the result of a forced landing, or two, in an Eggenfellner Subaru installation.) During ground runs, using a 5-gallon can, I found that the efi fuel pumps could not restore pressure once the tank had been allowed to run dry. When this occurred, the EFI pump would suck a big slug of air into the inlet side of the pump, loose pressure, and being unable to build psi equal to the pressure regulator setting, it would stop pumping fuel (vapor lock). The only way to restore operation was to crack open the system downstream of the pump until the slug of air could be passed on through the fuel pump. Not sure this meets your definiton of "vapor lock", but I think it does, but for a different reason than fuel vapor pressure. I have tested this system on the ground and it works as advertized. If the tank runs dry, switched to a full tank, the efi pump will restore pressure to the system within a few seconds. I urge all builders to run this test on their fuel system to determine whether or not their pumps are able to restore pressure after running a tank dry. Or, just don't ever run a tank dry. Mark S. On Wed, Aug 17, 2011 at 10:22 AM, Ernest Christley wrote: > Al Wick wrote: > >> I'm really concerned for some of these fuel designs. The fuel bleed has >> nothing to do with vapor lock. Virtually no effect at all. >> >> > > I don't know why others are doing it, but for me, the bleed has nothing at > all to do with vapor lock. Some conversations have been mixed together, so > I can see how that could be the impression. The point of the pressure bleed > is to bleed off the pressure after shutdown. > > I have a strong, positive head pressure going into my pumps. They, and the > regulator, are about 8" directly below the tank. Excess fuel goes back to > the opposite side of the tank from the pickup, and a single line goes > forward to feed the injectors. The fuel lines are arranged such that heat > soaking the lines to the point of boiling the gas will push liquid fuel down > hill and behind the firewall, isolating the gaseous gas with its heat at the > top of the line. Turning the pumps on will pressurize the line to 55psi, > returning most of the gaseous fuel back to a liquid state. The ECM is > programmed for a longer clearing pulse on hot start. > > The point of the bleed is to allow fuel to move back to the tank. I had > the issue of a the pressurized lines being perfectly sealed. The > pressurized fuel was finding the path of least resistance out, which just > happened to be out the injector and into the intake manifold where it sat as > a little puddle. Heat soaking the lines would not push liquid fuel downhill > and back behind the firewall. It would push more fuel into the manifold. A > puddle of gas sitting in a composite manifold, just above a hot exhaust > stack is just bad mojo. A poorly sealed regulator allows the pressure to > bleed off in about 5 seconds (give or take), isolating the hot fuel in front > of the firewall, and keeping the rest cool and out of the intake manifold. > > Got nuthin' to do with vapor lock. > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:** > 81/lists/flyrotary/List.html > --20cf3054ad49bb4bbf04aab5dca1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Al,
=A0
I would think that a well-designed=A0fuel system=A0with the pumps loca= ted as low as possible, in a=A0cool area,=A0and=A0a return system=A0should = not be troubled with vapor locking.=A0=A0Although I guess it could happen i= n Death Valley in=A0August if the a/c is left out in the sun for 8 hours, a= nd running auto gas.=A0 So far, I haven't had any problem here in Texas= (temps 105* today).=A0 =A0
=A0
My purpose for installing the bypass circuit was more critical to safe= flight.=A0 (The solution was=A0the result of a forced landing, or two,=A0i= n an Eggenfellner Subaru installation.)=A0 During ground runs, using a 5-ga= llon can, I found that the efi fuel pumps could not restore pressure once t= he tank had been allowed to run dry.=A0=A0When this occurred, the EFI pump= =A0would suck a big slug of air into the inlet side of the pump, loose pres= sure,=A0and being unable to build psi equal to the pressure regulator setti= ng, it would stop pumping fuel (vapor lock).=A0 The only way to restore ope= ration was to crack open the system downstream of the pump until the slug o= f air could be passed on through the fuel pump.=A0=A0Not sure this meets yo= ur definiton of "vapor lock", but I think it does, but for a diff= erent reason than fuel vapor pressure.
=A0
I have tested this system on the ground and it works as advertized.=A0= If the tank runs dry, switched to a full tank, the efi pump will restore p= ressure to the system within a few seconds.=A0 I urge all builders to run t= his test on their fuel system to determine whether or not their pumps are a= ble to restore pressure after running a tank dry.=A0 Or, just don't eve= r run a tank dry.
=A0
Mark S.


=A0
On Wed, Aug 17, 2011 at 10:22 AM, Ernest Christl= ey <echristley@a= tt.net> wrote:
Al Wick wrote:
I'm really concerned for som= e of these fuel designs. The fuel bleed has nothing to do with vapor lock. = Virtually no effect at all.
=A0

I don't know why others are doing it, but= for me, the bleed has nothing at all to do with vapor lock. =A0Some conver= sations have been mixed together, so I can see how that could be the impres= sion. =A0The point of the pressure bleed is to bleed off the pressure after= shutdown.

I have a strong, positive head pressure going into my pumps. =A0They, a= nd the regulator, are about 8" directly below the tank. =A0Excess fuel= goes back to the opposite side of the tank from the pickup, and a single l= ine goes forward to feed the injectors. =A0The fuel lines are arranged such= that heat soaking the lines to the point of boiling the gas will push liqu= id fuel down hill and behind the firewall, isolating the gaseous gas with i= ts heat at the top of the line. =A0Turning the pumps on will pressurize the= line to 55psi, returning most of the gaseous fuel back to a liquid state. = =A0The ECM is programmed for a longer clearing pulse on hot start.

The point of the bleed is to allow fuel to move back to the tank. =A0I = had the issue of a the pressurized lines being perfectly sealed. =A0The pre= ssurized fuel was finding the path of least resistance out, which just happ= ened to be out the injector and into the intake manifold where it sat as a = little puddle. =A0Heat soaking the lines would not push liquid fuel downhil= l and back behind the firewall. =A0It would push more fuel into the manifol= d. =A0A puddle of gas sitting in a composite manifold, just above a hot exh= aust stack is just bad mojo. =A0A poorly sealed regulator allows the pressu= re to bleed off in about 5 seconds (give or take), isolating the hot fuel i= n front of the firewall, and keeping the rest cool and out of the intake ma= nifold.

Got nuthin' to do with vapor lock.

-= -
Homepage: =A0h= ttp://www.flyrotary.com/
Archive and UnSub: =A0 http:/= /mail.lancaironline.net:81/lists/flyrotary/List.html

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