X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 24 Sep 2014 13:21:14 -0400 Message-ID: X-Original-Return-Path: Received: from [207.46.100.54] (HELO na01-by2-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 7172573 for lml@lancaironline.net; Wed, 24 Sep 2014 12:06:06 -0400 Received-SPF: pass receiver=logan.com; client-ip=207.46.100.54; envelope-from=ngeorge@continentalmotors.aero Received: from BLUPR04MB722.namprd04.prod.outlook.com (10.141.206.150) by BLUPR04MB723.namprd04.prod.outlook.com (10.141.206.152) with Microsoft SMTP Server (TLS) id 15.0.1039.15; Wed, 24 Sep 2014 16:05:28 +0000 Received: from BLUPR04MB722.namprd04.prod.outlook.com (10.141.206.150) by BLUPR04MB722.namprd04.prod.outlook.com (10.141.206.150) with Microsoft SMTP Server (TLS) id 15.0.1039.15; Wed, 24 Sep 2014 16:05:27 +0000 Received: from BLUPR04MB722.namprd04.prod.outlook.com ([10.141.206.150]) by BLUPR04MB722.namprd04.prod.outlook.com ([10.141.206.150]) with mapi id 15.00.1039.011; Wed, 24 Sep 2014 16:05:27 +0000 From: Neal George X-Original-To: Lancair Mailing List Subject: RE: [LML] Mechanical Fuel Pump Oddities Thread-Topic: [LML] Mechanical Fuel Pump Oddities Thread-Index: AQHP1+iD6TKLALaZyEWorcKdfOGHcpwQbeHg X-Original-Date: Wed, 24 Sep 2014 16:05:26 +0000 X-Original-Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [69.85.249.2] x-microsoft-antispam: BCL:0;PCL:0;RULEID:;SRVR:BLUPR04MB722;UriScan:; x-forefront-prvs: 03449D5DD1 x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(377454003)(199003)(189002)(31966008)(74316001)(54356999)(108616004)(76176999)(85306004)(50986999)(10300001)(95666004)(16601075003)(99286002)(101416001)(87936001)(21056001)(105586002)(106116001)(19625215002)(15202345003)(99396003)(106356001)(4396001)(2656002)(76482002)(120916001)(83322001)(19580405001)(97736003)(16236675004)(15975445006)(64706001)(92566001)(86362001)(19300405004)(107046002)(76576001)(20776003)(107886001)(81542003)(46102003)(85852003)(83072002)(19580395003)(74502003)(80022003)(81342003)(74662003)(79102003)(19617315012)(66066001)(77982003)(90102001)(33646002)(110136001)(24736002);DIR:OUT;SFP:1101;SCL:1;SRVR:BLUPR04MB722;H:BLUPR04MB722.namprd04.prod.outlook.com;FPR:;MLV:sfv;PTR:InfoNoRecords;A:1;MX:1;LANG:en; Content-Type: multipart/alternative; boundary="_000_ef50dec9fabc4f72a6f21199ca63c45eBLUPR04MB722namprd04pro_" MIME-Version: 1.0 X-Original-Return-Path: ngeorge@continentalmotors.aero X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:;SRVR:BLUPR04MB723; X-OriginatorOrg: continentalmotors.aero --_000_ef50dec9fabc4f72a6f21199ca63c45eBLUPR04MB722namprd04pro_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable ...so the best explanation could be "they do that". Yeah...elevated fuel temps, high altitude/low atmospheric pressure, increas= ed head differential due to climb attitude, vent restrictions (bugs and fue= l stains), and the engine-driven pump trying to suck fuel uphill thru the r= estrictions of fittings, valves and twisting hoses & tubes all conspire to = lower the system pressure. When the system pressure is lower than the vapo= r pressure of the fuel, it boils. I've also seen fuel lines and boost pumps leak air under suction that don't= leak fuel under pressure. When (before) your Dukes pump goes, consider CJ Aviation ( www.cjaviation.c= om ) for a replacement or overhaul... Neal From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Stev= e Colwell Sent: Wednesday, September 24, 2014 6:13 AM To: Lancair Mailing List Subject: [LML] Mechanical Fuel Pump Oddities Kevin, I had the same problem on a warm day with warm fuel from an above ground ta= nk. My solution is to leave Low Boost on all the time. The Dukes pump is = not rated for continuous operation but mine is still running at 200+ hours.= Another plus is, if your engine pump fails on takeoff, Low Boost will pro= bably keep the engine running (maybe at reduced power but still running). = I believe Continental recommends Low Boost above 10,000' so the best explan= ation could be "they do that". Steve Colwell IO-550 Legacy --_000_ef50dec9fabc4f72a6f21199ca63c45eBLUPR04MB722namprd04pro_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

…so the best explanation could be “they = do that”.

 

Yeah…elevated fuel temps, high altitude/low atmospheric p= ressure, increased head differential due to climb attitude, vent restrictions (bugs and fuel stains), and the engine-driven pump tryin= g to suck fuel uphill thru the restrictions of fittings, valves and twistin= g hoses & tubes all conspire to lower the system pressure.  When the system pressure is lower than the vapor pressure of the fue= l, it boils.

 

I’ve also seen fuel lines and boost pumps leak air under = suction that don’t leak fuel under pressure.

 

When (before) your Dukes pump goes, consider CJ Aviation ( www.cjaviation.com ) for a replac= ement or overhaul…

 

Neal  

 

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Steve Colw= ell
Sent: Wednesday, September 24, 2014 6:13 AM
To: Lancair Mailing List
Subject: [LML] Mechanical Fuel Pump Oddities

 

Kevin,

 

I had the same problem on a warm day with warm fuel = from an above ground tank.  My solution is to leave Low Boost on all t= he time.  The Dukes pump is not rated for continuous operation but min= e is still running at 200+ hours.  Another plus is, if your engine pump fails on takeoff, Low Boost will probably keep the= engine running (maybe at reduced power but still running).  I believe= Continental recommends Low Boost above 10,000’ so the best explanati= on could be “they do that”.

 

Steve Colwell  IO-550 Legacy

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