X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 23 Aug 2010 17:02:21 -0400 Message-ID: X-Original-Return-Path: Received: from imr-mb01.mx.aol.com ([64.12.207.164] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4440750 for lml@lancaironline.net; Mon, 23 Aug 2010 10:38:45 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.207.164; envelope-from=Sky2high@aol.com Received: from imo-ma02.mx.aol.com (imo-ma02.mx.aol.com [64.12.78.137]) by imr-mb01.mx.aol.com (8.14.1/8.14.1) with ESMTP id o7NEc5Do027930 for ; Mon, 23 Aug 2010 10:38:05 -0400 Received: from Sky2high@aol.com by imo-ma02.mx.aol.com (mail_out_v42.9.) id q.ca8.5d9c9b12 (37067) for ; Mon, 23 Aug 2010 10:38:03 -0400 (EDT) Received: from magic-m21.mail.aol.com (magic-m21.mail.aol.com [172.20.22.194]) by cia-db05.mx.aol.com (v129.4) with ESMTP id MAILCIADB051-90cb4c7287cb7; Mon, 23 Aug 2010 10:38:03 -0400 From: Sky2high@aol.com X-Original-Message-ID: <66dc7.72732477.39a3e1cb@aol.com> X-Original-Date: Mon, 23 Aug 2010 10:38:03 EDT Subject: Re: [LML] Vapor lock X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_66dc7.72732477.39a3e1cb_boundary" X-Mailer: AOL 9.5 sub 155 X-AOL-IP: 24.15.17.119 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_66dc7.72732477.39a3e1cb_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Hugh, Yes. Generally the fuel pressure sensor is located downstream of the engine fuel pump. Fuel pressure warnings occur when the fuel pressure drops below 12-14 psi (12psi is a Lyc IO320 min). For me, any pressure below 20 is an indication of vaporization for my IO 320 and the boost pump comes on. My standard pressure is 24-26 psi. 1. The engine driven pump can become super heated after the engine is stopped. It can then cause severe vaporization and cavitation itself for quite some time -- until is sees pressurized cooler fuel. 2. If the boost pump is mounted on the firewall, it can become over heated in the engine compartment. It is useful to open the oil filler door after the engine is stopped to allow hot air to escape that way. An LNC2 equipped with the main fuel tank as a header tank, the fuel is always at a small positive pressure to the boost pump mounted lower than that tank where the boost pump is self priming and should be able to overcome vaporization. However, it may initially have a problem pushing fuel through an overheated engine pump. I have experienced engine pump cavitation while slow taxiing at OSH and it was resolved by turning on the boost pump. For a hot start I turn the boost pump on even though the mixture control is set at idle cut-off for the initial attempt. Vaporization can be reduced by keeping even hot fuel under pressure. Scott Krueger In a message dated 8/23/2010 8:15:06 A.M. Central Daylight Time, hkb7ld@embarqmail.com writes: Has any one had problems with vapor lock on fuel injected LNC2 airplanes? I am not sure vapor lock is the problem but I have had the electric fuel pump cavitate and not develop pressure when trying to start after the engine is hot. Also how to you start a fuel injected engine with out electric fuel pump pressure? Thanks Hugh in Las Vegas the hot country --part1_66dc7.72732477.39a3e1cb_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Hugh,

Yes. Generally the fuel pressure sensor is located downstream= of the=20 engine fuel pump. Fuel pressure warnings occur when the fuel pressur= e=20 drops below 12-14 psi (12psi is a Lyc IO320 min). For= me,=20 any pressure below 20 is an indication of vaporization for my IO 320 and= the=20 boost pump comes on. My standard pressure is 24-26 psi.

1. The engine driven pump can become super heated after the engine is= =20 stopped. It can then cause severe vaporization and cavitation= itself=20 for quite some time -- until is sees pressurized cooler fuel.

2. If the boost pump is mounted on the firewall, it can bec= ome=20 over heated in the engine compartment. It is useful to open the oil= filler=20 door after the engine is stopped to allow hot air to escape that way.

An LNC2 equipped with the main fuel tank as a header tank, the fuel= is=20 always at a small positive pressure to the boost pump mounted lower= than=20 that tank where the boost pump is self priming and should be abl= e to=20 overcome vaporization. However, it may initially have a problem= =20 pushing fuel through an overheated engine pump.

I have experienced engine pump cavitation while slow taxiing at OSH= and it=20 was resolved by turning on the boost pump.

For a hot start I turn the boost pump on even though the mixture cont= rol is=20 set at idle cut-off for the initial attempt. Vaporization can be red= uced=20 by keeping even hot fuel under pressure.

Scott Krueger

In a message dated 8/23/2010 8:15:06 A.M. Central Daylight Time,=20 hkb7ld@embarqmail.com writes:

Has any one had problems with vapor loc= k on=20 fuel injected LNC2 airplanes?

I am not sure vapor lock is the problem= but I=20 have had the electric fuel pump cavitate and not develop pressure w= hen=20 trying to start after the engine is hot.

Also how to you start a fuel injected= engine with=20 out electric fuel pump pressure?

Thanks

Hugh in Las Vegas the hot country

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