X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 17 Jun 2011 13:46:36 -0400 Message-ID: X-Original-Return-Path: Received: from nm18-vm0.bullet.mail.bf1.yahoo.com ([98.139.213.138] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with SMTP id 5023783 for lml@lancaironline.net; Fri, 17 Jun 2011 13:33:38 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.213.138; envelope-from=mcmess1919@yahoo.com Received: from [98.139.212.146] by nm18.bullet.mail.bf1.yahoo.com with NNFMP; 17 Jun 2011 17:33:03 -0000 Received: from [98.139.211.199] by tm3.bullet.mail.bf1.yahoo.com with NNFMP; 17 Jun 2011 17:33:03 -0000 Received: from [127.0.0.1] by smtp208.mail.bf1.yahoo.com with NNFMP; 17 Jun 2011 17:33:03 -0000 X-Yahoo-Newman-Id: 233283.78707.bm@smtp208.mail.bf1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: I1Z3tcAVM1m29oKHwcEixUYyB6kvEOzSrthul_SCSVVk4nX lNlTe0U3DI0_zYRlH0.4_WSmxyr7BC5RwIWh4CiMO0t0JDZUptqnnnZ.rHhK .i.3zJQ_uD5Glr0rBAbRivClp7cXsnFs7ALi.AFAPGdeVUCEjZ.WzALbXw3H nlcG2Gwz6l4V7FUFnmTrdfKWPPtvNAJTK0n2sTN6PX_RQ1FnkHlFYqg6mB4p 4PEOM7lRuSQF36cWObN0G9huchNLlQmb44EHduyhrmGekhxn5stOsrQl6ds0 EI21klhPRiJXz_UDsb21ZtYM2CrAeDbc3nsQNyACFcB8NVriXya3J_pq8z7s 3FmNMdTWgJCrIKGNvbqNPFokOM_IGssjSP1w- X-Yahoo-SMTP: rK4i7HqswBC7mDE8.sOiWQeO4CeReXc- Received: from StevePC (mcmess1919@67.187.173.57 with login) by smtp208.mail.bf1.yahoo.com with SMTP; 17 Jun 2011 10:33:02 -0700 PDT From: "Steve Colwell" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: fuel pressure and fuel flow X-Original-Date: Fri, 17 Jun 2011 10:33:05 -0700 X-Original-Message-ID: <001a01cc2d14$9e4ca240$dae5e6c0$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001B_01CC2CD9.F1EDCA40" X-Mailer: Microsoft Office Outlook 12.0 thread-index: AcwtDgAEn2QVNoaCTL+Do2DtvrkzCQABNL3A Content-Language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_001B_01CC2CD9.F1EDCA40 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit The problem could be a slight change in the initial boiling point of 100LL. The specs for 100LL may allow refiners to vary just enough to cause fuel to start to bubble in the lines at a temperature and density altitude that was OK previously. The boost pump would solve this problem most of the time with 100LL; with auto fuel, maybe not. About leaks. Fuel has lower surface tension than air so it will leak when air won't. I learned this when air trapped in a fine screen Gascolator with a glass bowl in an Aircoupe. Fuel would pass thru the screen but the air bubble in the top would not! Steve Legacy At 6,500' the engine began surging. When we turned the auxiliary fuel pump on the engine immediately ran fine. We have now had the engine driven pump overhauled. We have pulled vacuum through the entire fuel system and we have no leaks. We replaced 100% of the flexible fuel lines. Metered and un-metered fuel pressures are reset and fine. We are at a loss as to what is causing our engine surging problem. Berni ------=_NextPart_000_001B_01CC2CD9.F1EDCA40 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

The problem could be a slight change in the initial boiling point of = 100LL. The specs for 100LL may allow refiners to vary just enough = to cause fuel to start to bubble in the lines at a temperature and = density altitude that was OK previously. The boost pump would = solve this problem most of the time with 100LL; with auto fuel, maybe = not.

About leaks. Fuel has lower surface tension than air so it will = leak when air won’t. I learned this when air trapped in a = fine screen Gascolator with a glass bowl in an Aircoupe. Fuel = would pass thru the screen but the air bubble in the top would = not!

Steve Legacy

At = 6,500’ the engine began surging. When we turned the = auxiliary fuel pump on the engine immediately ran fine. We have = now had the engine driven pump overhauled. We have pulled vacuum = through the entire fuel system and we have no leaks. We replaced = 100% of the flexible fuel lines. Metered and un-metered fuel = pressures are reset and fine. We are at a loss as to what is = causing our engine surging problem.

Berni =

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