X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qmta13.emeryville.ca.mail.comcast.net ([76.96.27.243] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTP id 5598506 for flyrotary@lancaironline.net; Wed, 13 Jun 2012 23:56:47 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.27.243; envelope-from=hoursaway1@comcast.net Received: from omta06.emeryville.ca.mail.comcast.net ([76.96.30.51]) by qmta13.emeryville.ca.mail.comcast.net with comcast id N3pj1j00516AWCUAD3wAVp; Thu, 14 Jun 2012 03:56:10 +0000 Received: from sz0081.ev.mail.comcast.net ([76.96.26.137]) by omta06.emeryville.ca.mail.comcast.net with comcast id N3wA1j00P2xV6SL8S3wAcP; Thu, 14 Jun 2012 03:56:10 +0000 Date: Thu, 14 Jun 2012 03:56:10 +0000 (UTC) From: hoursaway1@comcast.net To: Rotary motors in aircraft Message-ID: <68848644.93337.1339646170067.JavaMail.root@sz0081a.emeryville.ca.mail.comcast.net> In-Reply-To: Subject: Re: [FlyRotary] Re: Fuel presure question. MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_93336_1250371796.1339646170046" X-Originating-IP: [71.206.108.115] X-Mailer: Zimbra 6.0.13_GA_2944 (ZimbraWebClient - IE8 (Win)/6.0.13_GA_2944) ------=_Part_93336_1250371796.1339646170046 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Will check with fuel pressure tester .=C2=A0 Thanks Steve.=C2=A0 David.=20 ----- Original Message ----- From: "Steven W. Boese" =20 To: "Rotary motors in aircraft" =20 Sent: Wednesday, June 13, 2012 3:35:13 PM=20 Subject: [FlyRotary] Re: Fuel presure question.=20 =C2=A0=20 David,=20 It might be worthwhile to temporarily connect a mechanical gauge to the=C2= =A0pressurized section of the=C2=A0fuel system to verify that the fuel pres= sure sensing system is working correctly.=20 I have had a similar situation where the fuel pressure was lower after turn= ing on=C2=A0the second=C2=A0HP pump and then the fuel pressure was higher a= gain after turning off one of the pumps.=C2=A0 In my case, the problem was = caused by an aftermarket adjustable pressure regulator that had excessive f= riction in a moving piston seal.=C2=A0 The pressures weren't perfectly=C2= =A0reproducible and the problem was solved by a change in the design of the= fuel pressure regulator=C2=A0with an=C2=A0update kit.=C2=A0 I later change= d to the stock Mazda fuel pressure regulator and that has worked fine also.= =20 It may also be useful to look at the effect of disconnecting the vacuum lin= e at idle.=C2=A0 For my installation with the stock Mazda regulator, the fu= el pressure is close to 42 psi at full throttle or at idle with the vacuum = line to the regulator disconnected.=C2=A0 At idle with=C2=A0the vacuum line= connected, the=C2=A0fuel pressure is close to 36 psi.=20 Steve Boese=20 RV6A , 1986=C2=A013B NA, RD1A , EC2=20 =C2=A0=20 From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of = hoursaway1@comcast.net [hoursaway1@comcast.net]=20 Sent: Tuesday, June 12, 2012 5:11 PM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Fuel presure question.=20 Question about fuel pressure indications, at fast idle 2200 RPM, fuel press= ure is 42 PSI on EM2, if I switch on the back-up pump with the primary pump= the pressure drops to 35 PSI, can here both pumps running, if I switch off= either pump pressure goes back to 42 PSI.=C2=A0 My system is 13B, stock re= d injectors all four, pressure regulator is stock Mazda on the end of fuel = rail with vacume connection from dynamic chamber.=C2=A0 Thanks,=C2=A0 David= R. Cook=C2=A0 RV6A Rotary. ------=_Part_93336_1250371796.1339646170046 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit

Will check with fuel pressure tester. Thanks Steve. David.

From: "Steven W. Boese" <SBoese@uwyo.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, June 13, 2012 3:35:13 PM
Subject: [FlyRotary] Re: Fuel presure question.

David,

It might be worthwhile to temporarily connect a mechanical gauge to the pressurized section of the fuel system to verify that the fuel pressure sensing system is working correctly.

I have had a similar situation where the fuel pressure was lower after turning on the second HP pump and then the fuel pressure was higher again after turning off one of the pumps. In my case, the problem was caused by an aftermarket adjustable pressure regulator that had excessive friction in a moving piston seal. The pressures weren't perfectly reproducible and the problem was solved by a change in the design of the fuel pressure regulator with an update kit. I later changed to the stock Mazda fuel pressure regulator and that has worked fine also.

It may also be useful to look at the effect of disconnecting the vacuum line at idle. For my installation with the stock Mazda regulator, the fuel pressure is close to 42 psi at full throttle or at idle with the vacuum line to the regulator disconnected. At idle with the vacuum line connected, the fuel pressure is close to 36 psi.

Steve Boese

RV6A, 1986 13B NA, RD1A , EC2

From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of hoursaway1@comcast.net [hoursaway1@comcast.net]
Sent: Tuesday, June 12, 2012 5:11 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Fuel presure question.

Question about fuel pressure indications, at fast idle 2200 RPM, fuel pressure is 42 PSI on EM2, if I switch on the back-up pump with the primary pump the pressure drops to 35 PSI, can here both pumps running, if I switch off either pump pressure goes back to 42 PSI. My system is 13B, stock red injectors all four, pressure regulator is stock Mazda on the end of fuel rail with vacume connection from dynamic chamber. Thanks, David R. Cook RV6A Rotary.

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