Return-Path: Received: from [65.33.165.140] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WebUser 4.3c1) with HTTP id 727291 for flyrotary@lancaironline.net; Sun, 13 Feb 2005 13:08:49 -0500 From: "Marvin Kaye" Subject: Re: [FlyRotary] Re: Vapor Lock To: "Rotary motors in aircraft" X-Mailer: CommuniGate Pro WebUser Interface v.4.3c1 Date: Sun, 13 Feb 2005 13:08:49 -0500 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format="flowed" Content-Transfer-Encoding: 8bit A friend of mine with a Lancair ES stopped out to visit recently and after leaving the airplane parked on the ramp for perhaps 45 minutes, was unable to get the engine restarted. He has a Continental IO550 with a Dukes boost pump mounted to the engine side of the firewall, perhaps 15" higher than the fuel inlet level from the wing tanks. He confessed that he'd been fighting this battle for some time, and was anxious to come up with a solution. In order to get him started I pulled the air hose over to the wingtip, cut a little rubber gasket from a sheet of 1/16" silicone and applied about 10psi of pressure to the wing tank vent opening. This forced cool fuel from the tank up to the pump, displacing the vapor which had accummulated while it sat, and the engine started right up. I suggested that he install a facet pump and a check-valved bypass circuit down at the fuel inlet to push fuel up to the regular Dukes pump for when he's doing a hot start. He did the modification and the problem has never recurred. Other folks have reported fuel flow problems when they located their pumps between the engine and fuel selector instead of between the fuel selector and tanks... mostly the cause was air being sucked past the fuel selector's seals causing some air to be introduced into the fuel flow. Pushing fuel is always the better approach, and switching to that methodology has been known to cure a number of problems, these two mentioned are just a few that immediately come to mind. FWIW. "Barnhart" wrote: """ Al, I know what you mean about fuel being better pushed than sucked. """