X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nm7-vm0.access.bullet.mail.sp2.yahoo.com ([98.139.44.116] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with SMTP id 5096526 for flyrotary@lancaironline.net; Thu, 18 Aug 2011 14:41:33 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.44.116; envelope-from=keltro@att.net Received: from [98.139.44.97] by nm7.access.bullet.mail.sp2.yahoo.com with NNFMP; 18 Aug 2011 18:40:58 -0000 Received: from [98.139.44.76] by tm2.access.bullet.mail.sp2.yahoo.com with NNFMP; 18 Aug 2011 18:40:58 -0000 Received: from [127.0.0.1] by omp1013.access.mail.sp2.yahoo.com with NNFMP; 18 Aug 2011 18:40:58 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 783811.72378.bm@omp1013.access.mail.sp2.yahoo.com Received: (qmail 34802 invoked by uid 60001); 18 Aug 2011 18:40:58 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1313692858; bh=QfLSmQJM07ybHyRdtXZxXuWDyobbBX6ioUDpLenlI5I=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=yo0Ii+fiRkwfHcp+bYT1MeF1d7pcxyUwHgBlRCVcb5o2jtsMic6GiAsU4G3b7KCn9CK7IF9r874F0A5xv2G4wTOUCu/x0pH+Bv0CZ71zQKQSs6R9re0c4vRA9azBR19uFs3fXd9X09esv0XHq64BDJYKHOIVlR6qAVNQDUmDTtA= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=att.net; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=Y0k3Od6uYKCRbp4Ojr+Mf6FlYevmHfpqy9XqENrgTfE8UBJds/MxPS+Nc72tbdcEg8lvjiwLrA63BS8DfeyPN6VCT4g4V+/GaFqmJId3aASFWBXo8JARcUVyzEm+6vTjOgoYV1XmG3DmHv/iTvbf9/kx5RUphv+os+QEOyTspw8=; X-YMail-OSG: wAsGjp0VM1n7e6MdOh3kMCPanZel47FdedJrcNzQHLdSohJ KA3.GJ9inmbOEtVz8XaY3U1ntapIqC0P6wnkvmD9ifWoDoAAWjT4m_cdwoYt saWYl.aEz7Trz6pxj1A83_MoOA11ECPuktHgUiUf.iaFpawco1cUpRuIijEw dGpsDV.FGA7uc5KX4nV5q7rW7Ihc3lezmYdUs5GhILXedWu4njvq7p5HKSrZ AoPtdvznPSmJNNmU6QJV1ffWQSghWHY2I9TNjig6FDL4YHEe_u5MwqRxUG1M oNqnMBAzvCshNnahohueB.D_4IT.aKXmhrn3CdlxqmvkljBS9Mtjq2b4Oy2v FxnYj3jaMyB8FAnPgJfF_zo3hIf3u.L.JohJ_Smiuy0SNRni0bTohdlE7NU5 yci0cEneIwObGMFTfr48hGh_Af_yIRNviyxLpBzK9xQxNk8ZnoM.ot50zt9X B6mMUT3pDJ5d1DgjdPbJgGeAIR0a6ifMovhQoyvyobb9Khon.dCuFnpttpyz Kafz_fpRMQIe4F6zca8RfQWI2kWQsPt0qbYi46TWYs3TKKXKe3FtHS7hphdo VtgYfj0Uab6ZzqyyGuKoH2FlWHqqn8pOU2ZKO9L0yoZ.wfgaYobuDYp4gc1q jdTu5lRgTZFC1M9u2vp9JDWNBv6Kk7gMaCvLwl_6JK3MgnKvmHTxBiViSFwf p7JlZXksWveL6bmppAeOcCY9TFw-- Received: from [208.114.40.71] by web83908.mail.sp1.yahoo.com via HTTP; Thu, 18 Aug 2011 11:40:58 PDT X-Mailer: YahooMailWebService/0.8.113.313619 References: Message-ID: <1313692858.25370.YahooMailNeo@web83908.mail.sp1.yahoo.com> Date: Thu, 18 Aug 2011 11:40:58 -0700 (PDT) From: Kelly Troyer Reply-To: Kelly Troyer Subject: Re: Dennis Haverlah Fuel System...or any others, for that matter. To: Rotary motors in aircraft MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-530921352-1313692858=:25370" --0-530921352-1313692858=:25370 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Mark,=0A=A0=A0=A0=A0=A0 I am using the duplex valve sourced from Buelent Al= iev's company "Enginegear"=A0which=0Ahas 1/2 inch pipe inlets and 3/8 inch = pipe return........They are=A0pricey but Buelent made them =0Aavailable to = the group a few years ago at a steep discount............But what is your l= ife worth !!=0A=A0=A0=A0=A0 Glad to hear you are using -8 feed to your pump= s.............The Holley Gerotor pumps look=0Abulletproof and just happen t= o have -8 inlets and outlets...........Said to be good for 3000 hours=0Aand= even usable for diesel engines.............What are the Andair valve=A0inl= et/outlet sizes ??..........=0A=A0=0A=A0=A0http://www.enginegearonline.com/= products/6-Port-ball-valve.html=0A=0AKelly Troyer=0A"DYKE DELTA JD2" (Event= ually)=0A"13B ROTARY"_ Engine=0A"RWS"_RD1C/EC2/EM2=0A"MISTRAL"_Backplate/Oi= l Manifold=0A"TURBONETICS"_TO4E50 Turbo=0A=0AFrom: Mark Steitle =0ATo: Rotary motors in aircraft =0AS= ent: Thursday, August 18, 2011 1:14 PM=0ASubject: [FlyRotary] Re: Dennis Ha= verlah Fuel System...or any others, for that matter.=0A=0A=0AKelly,=A0 =0A= =0AYou can use a -16, but you'll still be limited by the inlet/outlet size = of the Andair valve. =A0I'm using -8 supply with a -6 return. =A0These were= upsized from original -6/-4 called for in the plans. =A0=0A=0AMark=0A=0A= =0AOn Thu, Aug 18, 2011 at 12:37 PM, Kelly Troyer wrote:= =0A=0AAl,=0A>=A0 Sounds like fuel line to the EFI pump (external pump) need= s to be about AN-8 or=0A>even AN-10 instead of the typical AN-6 used by mos= t............=0A>=0A>=0A>Kelly Troyer=0A>"DYKE DELTA JD2" (Eventually)=0A>"= 13B ROTARY"_ Engine=0A>"RWS"_RD1C/EC2/EM2=0A>"MISTRAL"_Backplate/Oil Manifo= ld=0A>"TURBONETICS"_TO4E50 Turbo=0A>=0A>=0A>From: Al Wick = =0A>=0A>To: Rotary motors in aircraft =0A>Sen= t: Thursday, August 18, 2011 12:15 PM =0A>=0A>Subject: [FlyRotary] Re: Denn= is Haverlah Fuel System...or any others, for that matter.=0A>=0A>=0A><=A0Ma= rk's problem can best be described as an "Air =0A>=A0=0A>I'd describe it as not having "wet fuel inlet". When you turn = that fuel valve=A0"on" the first time, if inlet gets wet, you've nailed an = important design characteristic. =0A>You can simulate this with clear hose = and water. Seal off one end of hose. No air leaks allowed. Then pour water = in other end. If water makes it to closed end, you've got a good design. It= 's that simple. =0A>You'll notice that small diam hose doesn't behave the s= ame. What happens when I add filter to the hose? What if I put a loop in th= e line? You are asking the air at capped end to displace. The air has to be= able to move toward open end of tube. Play with it, pretty interesting. = =0A>=A0=0A>If your plumbing is already done, you can tape clear hose to plu= mbing and do the test with water. =0A>=A0=0A>All you are doing is convertin= g theory to facts. Important concept. =0A>=A0=0A>-al wick=0A>=A0=0A>=A0----= - Original Message ----- =0A>From: Kelly Troyer =0A>>To: Rotary motors in a= ircraft =0A>>Sent: Wednesday, August 17, 2011 12:40 PM=0A>>Subject: [FlyRot= ary] Dennis Haverlah Fuel System...or any others, for that matter.=0A>>=0A>= >=0A>>Al , Mark , Ernest=A0and All,=0A>>=A0=0A>>=A0 Perhaps a=A0name change= for the problem is in order.............Instead of an=0A>>actual "Fuel Vap= or Lock" Mark's problem can best be described as an "Air=0A>>Lock" in the p= ressure line=A0(Or Air Entrapment Lock)..........Ernest's problem=0A>>of in= jectors that leak down fuel (into the manifold or the engine with potential= =0A>>flooding or the fire hazard of dripping fuel in the cowl) has the same= solution =0A>>(bypass orifice) either external or internal to the regulato= r.......Both problems=0A>>no matter what you call them can be cured with th= e same solution.............=0A>>=A0=0A>>=A0=A0 =A0Al as for the leaky inje= ctors it would be great if these things did not wear=0A>>over time but they= do eventually become unable to hold pressure and will=0A>>exhibit leak-dow= n at some rate........Unfortunately the Rotary engine is much=0A>>more pron= e to flooding and hard starting if this fuel ends up in the Rotor=0A>>chamb= er..........If the primary injectors=A0are left in their stock positions an= d are=0A>>leaky this is a direct route to the Rotor............The secondar= y injectors may=0A>>or may not be a problem depending position and/or manif= old design...........=0A>>=A0=A0 =0A>>=A0=A0=A0=A0The bottom line is both p= otential problems can be averted with a simple=0A>>bypass orifice..........= ...As for an actual "Fuel Vapor Lock" as you say this is=0A>>a different pr= oblem and can be addressed by careful attention to fuel pump=0A>>positionin= g (external or in-tank) ,supply tube (or hose) size, low restriction=0A>>fi= lters to pump inlet, heat shielding if appropriate, etc................IMHO= =A0=0A>>=0A>>=0A>>Kelly Troyer=0A>>"DYKE DELTA JD2" (Eventually)=0A>>"13B R= OTARY"_ Engine=0A>>"RWS"_RD1C/EC2/EM2=0A>>"MISTRAL"_Backplate/Oil Manifold= =0A>>"TURBONETICS"_TO4E50 Turbo=0A>>=0A>>=0A>>From: Mark Steitle =0A>>To: Rotary motors in aircraft = =0A>>Sent: Wednesday, August 17, 2011 1:46 PM =0A>>=0A>>Subject: [FlyRotary= ] Re: Dennis Haverlah Fuel System...or any others, for that matter.=0A>>=0A= >>=0A>>Al, =0A>>=0A>>You wrote,"You also test it without the bleed line?"= =A0=0A>>=0A>>Yes, the test led to the search for a solution.=A0 You can see= the "bypass circuit" on Egg's fuel system schematic at http://www.eggenfel= lneraircraft.com/Manual-Updates/EarlyManualFuel.html.=A0 This is=A0what I= =A0incorporated into my=A0fuel system, and it solved the problem.=A0 Its be= en quite a few years now, but I=A0may still have=A0some of the posts on the= Eggenfellner=A0list=A0that occurred in search for this as the final soluti= on.=0A>>=A0=0A>>You wrote,"FWIW, everything you describe is not vapor lock,= has nothing to do with vapor lock."=A0 =0A>>=0A>>As I said, I'm not sure i= f my condition fits the definition of "vapor lock", but that's what someone= labeled it, and it stuck.=A0 The problem is that EFI pumps don't=A0draw or= push air very well.=A0 So, if the flowing fuel is replaced by air due to a= n empty tank, the pump keeps running, but essentially=A0stops pumping fuel.= =A0 With a 40# spring in the downstream circuit, it is virtually impossible= for the pump to pass the air=A0even though=A0the selector valve has been s= wiched to the full tank.=A0 I would agree that the fuel injectors should be= able to pass the air, provided the prop is still turning.=A0 (This was not= the case with my ground test.) The bypass circuit ensures that flow will= =A0be restored as soon as the bubble=A0passes through the pump and=A0the fu= el pump regains its prime.=A0 =0A>>=0A>>Mark S.=0A>>=0A>>=0A>>On Wed, Aug 1= 7, 2011 at 12:06 PM, Al Wick wrote:=0A>>=0A>>>>=0A>>>Instead of speculations, you can actually measure how good it= is. A pump, clear fuel lines, and water instead of fuel. Pinch fuel line w= ith pliers to increase pressure drop.=A0 Watch bubbles come out of solution= . Hear the rattle from pump due to it's inability to flow air. =0A>>>If you= also put a pressure gage on pump inlet, you can see how fine fuel filter i= ncreases risk. You can see how small diameter tubing increases risk, heat, = head pressure, etc etc. =0A>>>=A0=0A>>>>= >Egg had one forced landing. It was caused by vapor lock. Absolutely NOTHIN= G to do with the lack of bleed line. A day later, Jan made it to the crash = site. Pump would not flow fuel until he cracked the line loose. This is sim= ply because the inlet to pumps was not wet. He did not understand this. He = just reacted to symptoms. Nothing to do with vapor lock. Remember, this was= crash site. Who knows what attitude plane was at. As I described, if you s= crewed up your plumbing from tank to pump, then pump is not self priming. = =0A>>>=0A>>>=0A>>>>>You also test it without the bleed line? =0A>>>=0A>>>FWIW, everyth= ing you describe is not vapor lock, has nothing to do with vapor lock. =0A>= >>=A0-al wick=0A>>>=A0=0A>>>----- Original Message ----- =0A>>>>From: Mark = Steitle =0A>>>>To: Rotary motors in aircraft =0A>>>>Sent: Wednesday, August= 17, 2011 9:19 AM=0A>>>>Subject: [FlyRotary] Re: Dennis Haverlah Fuel Syste= m...or any others, for that matter.=0A>>>>=0A>>>>=0A>>>>Al,=0A>>>>=0A>>>>I = would think that a well-designed=A0fuel system=A0with the pumps located 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 in Death= Valley in=A0August if the a/c is left out in the sun for 8 hours, and runn= ing auto gas.=A0 So far, I haven't had any problem here in Texas (temps 105= * today).=A0 =A0 =0A>>>>=0A>>>>My purpose for installing the bypass circuit= was more critical to safe flight.=A0 (The solution was=A0the result of a f= orced landing, or two,=A0in an Eggenfellner Subaru installation.)=A0 During= ground runs, using a 5-gallon can, I found that the efi fuel pumps could n= ot restore pressure once the tank had been allowed to run dry.=A0=A0When th= is occurred, the EFI pump=A0would suck a big slug of air into the inlet sid= e of the pump, loose pressure,=A0and being unable to build psi equal to the= pressure regulator setting, it would stop pumping fuel (vapor lock).=A0 Th= e 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.=A0= =A0Not sure this meets your definiton of "vapor lock", but I think it does,= but for a different reason than fuel vapor pressure.=0A>>>>=0A>>>>I have t= ested 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 pressure to th= e system within a few seconds.=A0 I urge all builders to run this test on t= heir fuel system to determine whether or not their pumps are able to restor= e pressure after running a tank dry.=A0 Or, just don't ever run a tank dry.= =0A>>>>=0A>>>>Mark S.=0A>>>>=0A>>>>=0A>>>>=A0=0A>>>>On Wed, Aug 17, 2011 at= 10:22 AM, Ernest Christley wrote:=0A>>>>=0A>>>>Al Wic= k wrote:=0A>>>>>=0A>>>>>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.=0A>>>>>>=A0=0A>>>>>>=0A>>>>>I don't know why others are doing it, but = for me, the bleed has nothing at all to do with vapor lock. =A0Some convers= ations have been mixed together, so I can see how that could be the impress= ion. =A0The point of the pressure bleed is to bleed off the pressure after = shutdown.=0A>>>>>=0A>>>>>I have a strong, positive head pressure going into= my pumps. =A0They, and 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 line goes forward to feed the injectors. =A0The fuel lines a= re arranged such that heat soaking the lines to the point of boiling the ga= s will push liquid fuel down hill and behind the firewall, isolating the ga= seous gas with its heat at the top of the line. =A0Turning the pumps on wil= l 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.=0A>>>>>=0A>>>>>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 pressurized fuel was finding the path of least resistance o= ut, which just happened 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 downhill and back behind the firewall. =A0It would push more fu= el into the manifold. =A0A puddle of gas sitting in a composite manifold, j= ust above a hot exhaust stack is just bad mojo. =A0A poorly sealed regulato= r allows the pressure to bleed off in about 5 seconds (give or take), isola= ting the hot fuel in front of the firewall, and keeping the rest cool and o= ut of the intake manifold.=0A>>>>>=0A>>>>>Got nuthin' to do with vapor lock= .=0A>>>>>=0A>>>>>--=0A>>>>>Homepage: =A0http://www.flyrotary.com/=0A>>>>>Ar= chive and UnSub: =A0 http://mail.lancaironline.net:81/lists/flyrotary/List.= html=0A>>>>>=0A>>>>=0A>>=0A>>=0A>>--=0A>>Homepage:=A0 http://www.flyrotary.= com/=0A>>Archive and UnSub:=A0 http://mail.lancaironline.net:81/lists/flyro= tary/List.html=0A>>=0A>>=0A>>=0A>=0A> --0-530921352-1313692858=:25370 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Mark,
      I am using the du= plex valve sourced from Buelent Aliev's company "Enginegear"&nb= sp;which
<= SPAN style=3D"RIGHT: auto" id=3Dyiv117349295yui_3_2_0_14_1313691145859468>h= as 1/2 inch pipe inlets and 3/8 inch pipe return........They are price= y but Buelent made them
available to the gro= up a few years ago at a steep discount............But what is your life wor= th !!
   &n= bsp; Glad to hear you are using -8 feed to your pumps.............The Holle= y Gerotor pumps look
bulletproof and just= happen to have -8 inlets and outlets...........Said to be good for 3000 ho= urs
and even usable for diesel engines........= .....What are the Andair= valve inlet/outlet sizes ??..........
 
 
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
= "RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"= TURBONETICS"_TO4E50 Turbo

From: Mark Steitle <mstei= tle@gmail.com>
To: Ro= tary motors in aircraft <flyrotary@lancaironline.net>
Sent: Thursday, August 18, 2011 1:14 PM=
Subject: [FlyRotary] Re= : Dennis Haverlah Fuel System...or any others= , for that matter.

Kelly, =20

You can use a -16, but you'll still be limited by the inlet/outlet siz= e of the Andair valve.  I'm using -8 sup= ply with a -6 return.  These were upsized from original -6/-4 called for in the plans.  

Mark

On Thu, Aug 18, 2011 at 12:37 PM, Kell= y Troyer <keltro@att.net>= wrote:
Al,
  Sounds like fuel line to the EFI pump (external pump) needs to be about AN-8 or
even AN-10 instead of the typical AN-6 used by most............<= VAR>
 
Kelly Troyer
"DYKE = DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/E= M2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo

From: Al Wick <a= lwick@juno.com>=20

To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Thursday, August 18, 2011 12:15 PM= =20

Subjec= t: [FlyRotary] Re: Dennis Haverlah= Fuel System...or any others, for that matter.

< Mark's problem can best be descr= ibed as an "Air=20
<Lock" in the pressure line
 
I'd describe it as not having "wet fuel inlet". When you turn th= at fuel valve "on" the first time, if inlet gets wet, you've nailed an= important design characteristic.
You can simulate this with clear hose and water. Seal off one en= d of hose. No air leaks allowed. Then pour water in other end. If water mak= es it to closed end, you've got a good design. It's that simple.
You'll notice that small diam hose doesn't behave the same. What= happens when I add filter to the hose? What if I put a loop in the line? Y= ou are asking the air at capped end to displace. The air has to be able to = move toward open end of tube. Play with it, pretty interesting.
 
If your plumbing is already done, you can tape clear hose to plu= mbing and do the test with water.
 
All you are doing is converting theory to facts. Important conce= pt.
 
-al wick
 
 
----- Original Message -----
From: Kelly= Troyer
To: = Rotary motors in aircraft
Sent: Wednesday, August 17, 2011 12:40 PM
Subject:= [FlyRotary] Dennis Haverlah Fuel System.= ..or any others, for that matter.

Al , Mark , Ernest and All,
 
  Perhaps a name change for the problem is in order...= ..........Instead of an
actual "Fuel Vapor Lock" Mark's problem can best be described as= an "Air
Lock" in the pressure line (Or Air Entrapment Lock)........= ..Ernest's problem
of injectors that leak down fuel (into the manifold or the engin= e with potential
flooding or the fire hazard of dripping fuel in the cowl) has th= e same solution
(bypass orifice) either e= xternal or internal to the regulator.......Both problems
no matter what you call them can be cured with the same solution= .............
 
    Al as for the leaky injectors it would be gre= at if these things did not wear
over time but they do eventually become unable to hold pressure = and will
exhibit leak-down at some= rate........Unfortunately the Rotar= y engine is much
more prone to flooding and hard starting if this fuel ends up in= the Rotor
chamber..........If the primary injectors are left in their= stock positions and are
leaky this is a direct route to the Rotor............The seconda= ry injectors may
or may not be a problem depending position and/or manifold desig= n...........
  
    The bottom line is both potential problems can be averted with a simple
bypass orifice...........= ..As for an actual "Fuel Vapor Lock" as you say this is
a different problem and can be addressed by careful attention to= fuel pump
positioning (external or in-tank= ) ,supply tube (or hose) size, low restriction
filters to pump inlet, heat shielding if appropriate, etc....= ............IMHO 
 
Kelly Troyer
"= DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS= "_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_= TO4E50 Turbo

From: Mark Steitle <msteitle@= gmail.com>
To: Ro= tary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wednesday, August 17, 2011 1:46 PM=20

Subjec= t: [FlyRotary] Re: Dennis Hav= erlah Fuel System...or any others, for that matter.

Al,
 
You wrote,"You also test it without the bleed line?"&= nbsp;
 
Yes, the test led to the search for a solution.  You can see the = "bypass circuit" on Egg's fuel system schematic at http://www.eggenfellneraircraft.com/Manual-Updates/EarlyMan= ualFuel.html.  This is what I incorporated into my = fuel system, and it solved the problem.  Its been quite a few years no= w, but I may still have some of the posts on the Eggenfellner list that oc= curred in search for this as the final solution.
 
You wrote,= "FWIW, everythin= g you describe is not vapor lock, has nothing to do with vapor lock." =
 
As I said, I'm not sure if my condition fits the definition of "vapor = lock", but that's what someone labeled it, and it stuck.  The problem = is that EFI pumps d= on't draw or push air very well.  So, if the flowing fuel is repl= aced by air due to an empty tank, the pump keeps running, but essentially&n= bsp;stops pumping fuel.  With a 40# spring in the downstream circuit, = it is virtually impossible for the pump to pass the air even though&nb= sp;the selector valve has been swiched to the full tank.  I would agree that the fuel inj= ectors should be able to pass the air, provided the prop is still turning.&= nbsp; (This was not the case with my ground test.) The bypass circuit ensur= es that flow will be restored as soon as the bubble passes throug= h the pump and the fuel pump regains its prime. 
 
Mark S.

On Wed, Aug 17, 2011 at 12:06 PM, Al Wick <alwick@juno.com> wro= te:
<I would think that a well-designed fuel system with the pumps loca= ted as low as possible
 
Instead of speculations, you can actually = measure how good it is. A pump, clear fuel lines, and water instead of fuel= . Pinch fuel line with pliers to increase pressure drop.  Watch bubble= s come out of solution. Hear the rattle from pump due to it's inability to = flow air.
If you also put a pressure gage on pump in= let, you can see how fine fuel filter increases risk. You can see how small= diameter tubing increases risk, heat, head pressure, etc etc.
 
<the result of a forced landing
Egg had one forced landing. It was caused by vapor lock. Absolutely NO= THING to do with the lack of bleed line. A day later, Jan made it to the cr= ash site. Pump would not flow fuel until he cracked the line loose. This is= simply because the inlet to pumps was not wet. He did not understand this.= He just reacted to symptoms. Nothing to do with vapor lock. Remember, this= was crash site. Who knows what attitude plane was at. As I described, if y= ou screwed up your plumbing from tank to pump, then pump is not self primin= g.
 
<tested this system on the ground and it works as advertized
You also test it without the bleed line?
 
FWIW, everything you describe is not vapor lock, has nothing = to do with vapor lock.
 
-al wick
 
----- Origi= nal Message -----
From: Mark Steitle=
To: = Rotary motors in aircraft
Sent: Wednesday, August 17, 2011 9:19 AM
Subject:= [FlyRotary] Re: Dennis Haverlah Fuel System...or any others, for that matter.

Al,
 
I would think that a well-designed fuel system with the pump= s located as low as possible, in a cool area, and a return s= ystem should not be troubled with vapor locking.  Although I= guess it could happen in Death Valley in August if the a/c is left ou= t 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 tw= o, in an Eggenfellner= Subaru installation.)  During ground runs, using a 5-gallon ca= n, I found that the efi fuel pumps could not restore pressure once the tank had been allowed t= o 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 (va= por lock).  The only way to restore operation was to crack open the sy= stem downstream of the pump until the slug of air could be passed on throug= h the fuel pump.  Not sure this meets your definiton of "vapor lock", but I thi= nk 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 run= s dry, switched to a full tank, the efi<= /SPAN> 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 ru= nning 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 <echristley@att.net> wrote:
Al Wick wrote:
I'm really concerned for some of these fuel designs. T= he 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 pres= sure after shutdown.

I have a strong, positive head pressure going i= nto my pumps.  They, and the regulator, are about 8" directly below th= e tank.  Excess fuel goes back to the opposite side of the tank from t= he 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 bo= iling 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.  Turn= ing the pumps on will pressurize the line to 55psi, returning most of the g= aseous 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 manifo= ld 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), isolat= ing the hot fuel in front of the firewall, and keeping the rest cool and ou= t of the intake manifold.

Got nut= hin' to do with vapor lock.
<= BR>--
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