Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Tue, 06 May 2003 09:08:24 -0400 Message-ID: X-Original-Return-Path: Received: from ms-smtp-03.southeast.rr.com ([24.93.67.84] verified) by logan.com (CommuniGate Pro SMTP 4.1b4) with ESMTP id 2334960 for flyrotary@lancaironline.net; Tue, 06 May 2003 08:38:59 -0400 Received: from mail4.carolina.rr.com (fe4 [24.93.67.51]) by ms-smtp-03.southeast.rr.com (8.12.5/8.12.2) with ESMTP id h46CbWMq023785 for ; Tue, 6 May 2003 08:37:32 -0400 (EDT) Received: from o7y6b5 ([24.93.78.62]) by mail4.carolina.rr.com with Microsoft SMTPSVC(5.5.1877.757.75); Tue, 6 May 2003 08:41:00 -0400 X-Original-Message-ID: <001801c313cd$72cbfb20$1702a8c0@WorkGroup> From: "Ed Anderson" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: fuel pump suction? X-Original-Date: Tue, 6 May 2003 08:46:00 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 > If you are going > to have a boost pump (highly recommended if your RV-3 is using wing tanks) > -------------------- > > ===> Hi Ed. So I guess they have more suction than advertised. I will be > using wing tanks, with no header tank, so why do you highly recommend a > boost pump? I don't see the purpose, especially if the EFI pumps are > located below the fuel level. > > Rusty > Good question, Rusty. I guess I do it because I'm kind of a belt and suspenders type guy. But, here is my rationale, Reason 1: is that I found on a few occasions when I used MOGAS on a HOT day with a longer than normal ground time, I could tell the fuel was percolating (fluctuations in fuel pressure). Turning on the low pressure boost pump provides enough head pressure to eliminate it. Your set up may be such that you don't need to be concerned about vapor lock - but, I have that small header tank on the firewall. Reason 2: Should your line go dry (run a wing tank dry - I umm have done that on occasion - sometimes even intentional {:>)), the boost pump seems to fill the empty fuel line quicker - could be just perception since I've never timed how long it took to get fuel pressure back by either method.. Having stated that, by your decision to mount your tanks on the floor below the level of your wing tanks, I wouldn't think you would have problems. Ed