Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Mon, 29 Nov 2004 13:17:15 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d22.mx.aol.com ([205.188.144.208] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 549727 for lml@lancaironline.net; Mon, 29 Nov 2004 12:07:03 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.144.208; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-d22.mx.aol.com (mail_out_v37_r3.8.) id q.15.390da34a (25305) for ; Mon, 29 Nov 2004 12:06:21 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <15.390da34a.2edcb10d@aol.com> X-Original-Date: Mon, 29 Nov 2004 12:06:21 EST Subject: Re: [LML] Re: Cooling the TSIO550/fuel starvation with change of fuel tank X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1101747981" X-Mailer: AOL Strauss Beta Client sub 1180 -------------------------------1101747981 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 11/29/2004 10:23:21 A.M. Central Standard Time, MikeEasley@aol.com writes: I have no knowledge of that pump. Is it a single speed? I got my pump through Lancair. I don't have any residual fuel pressure after shutdown. I'm only used my pump for priming at engine start, never in flight. Mike, Lycoming injected engine setups usually retain pressure in the line from the pump (electric) to the throttle body if the engine is shut down via idle-cutoff. There is no "return line." Continental injected engines have a return line to carry excess throttle body fuel back to the selected tank and it is unlikely that any pressure would be retained in lines after shut down. However, this design (return line) is very useful: 1. A recommended hot start procedure is to just run the electric pump for two full minutes to charge the system with cool fuel and remove heat soaking from such things as the engine driven pump - heat that can cause cavitation and vaporization of the fuel - . 2. Before startup, Someone suggested running the pump for a while on the none engine-start tank and, thus, has not experienced tank switching hiccups in flight. This may be that the unused line is just full of air (fuel drained out or cooked out after a long ago shutdown) and filling it and the return line is useful for the later switch. 3. Turning on the "boost" pump (any engine) during the tank switch seems prudent in that it can assist in driving out any air, especially in the case that the engine pump starts to cavitate. Of course, this all depends on the arrangement of the components - making sure that the boos pump is not slowed down because it is full of air also. Scott Krueger AKA Grayhawk N92EX IO320 Aurora, IL (KARR) Some Assembly Required Using Common Hand Tools. -------------------------------1101747981 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 11/29/2004 10:23:21 A.M. Central Standard Time,=20 MikeEasley@aol.com writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

I have no knowledge of that pump. Is it a single speed? I= got=20 my pump through Lancair. I don't have any residual fuel pressure aft= er=20 shutdown. I'm only used my pump for priming at engine start, never i= n=20 flight.

Mike,

Lycoming injected engine setups usually retain pressure in the line fro= m=20 the pump (electric) to the throttle body if the engine is shut down via= =20 idle-cutoff. There is no "return line."

Continental injected engines have a return line to carry excess throttl= e=20 body fuel back to the selected tank and it is unlikely that any pressur= e=20 would be retained in lines after shut down. However, this design=20 (return line) is very useful:

1. A recommended hot start procedure is to just run the electric pump f= or=20 two full minutes to charge the system with cool fuel and remove heat=20 soaking from such things as the engine driven pump - heat that can caus= e=20 cavitation and vaporization of the fuel - .

2. Before startup, Someone suggested running the pump for a while on th= e=20 none engine-start tank and, thus, has not experienced tank switching=20 hiccups in flight. This may be that the unused line is just full of ai= r=20 (fuel drained out or cooked out after a long ago shutdown) and filling it an= d=20 the return line is useful for the later switch.

3. Turning on the "boost" pump (any engine) during the tank switch seem= s=20 prudent in that it can assist in driving out any air, especially in the= =20 case that the engine pump starts to cavitate. Of course, this all depe= nds=20 on the arrangement of the components - making sure that the boos pump is not= =20 slowed down because it is full of air also.=20

Scott Krueger=20 AKA Grayhawk
N92EX IO320 Aurora, IL (KARR)

Some Assembly Required=20
Using Common Hand Tools.

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