X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from aspensprings.uwyo.edu ([129.72.10.32] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTPS id 5597877 for flyrotary@lancaironline.net; Wed, 13 Jun 2012 15:35:51 -0400 Received-SPF: none receiver=logan.com; client-ip=129.72.10.32; envelope-from=SBoese@uwyo.edu Received: from ponyexpress-ht3.uwyo.edu (extlb.uwyo.edu [172.26.4.4]) by aspensprings.uwyo.edu (8.14.4/8.14.4) with ESMTP id q5DJZEwa003159 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL) for ; Wed, 13 Jun 2012 13:35:14 -0600 (MDT) (envelope-from SBoese@uwyo.edu) Received: from ponyexpress-m10.uwyo.edu ([fe80::60dd:cb9e:6f71:3d48]) by ponyexpress-ht3.uwyo.edu ([fe80::4cde:db24:a0a9:ba5%15]) with mapi id 14.01.0339.001; Wed, 13 Jun 2012 13:35:14 -0600 From: "Steven W. Boese" To: Rotary motors in aircraft Subject: RE: [FlyRotary] Fuel presure question. Thread-Topic: [FlyRotary] Fuel presure question. Thread-Index: AQHNSPDIRPF48xhNFkW9t951iHGraJb4n/mO Date: Wed, 13 Jun 2012 19:35:13 +0000 Message-ID: <3E8191F276108F4481AB0721BBA9269E05C4C8C2@ponyexpress-m10.uwyo.edu> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [75.244.193.93] Content-Type: multipart/alternative; boundary="_000_3E8191F276108F4481AB0721BBA9269E05C4C8C2ponyexpressm10u_" MIME-Version: 1.0 --_000_3E8191F276108F4481AB0721BBA9269E05C4C8C2ponyexpressm10u_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable David, It might be worthwhile to temporarily connect a mechanical gauge to the pre= ssurized section of the fuel system to verify that the fuel pressure sensin= g system is working correctly. I have had a similar situation where the fuel pressure was lower after turn= ing 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 af= termarket adjustable pressure regulator that had excessive friction in a mo= ving piston seal. The pressures weren't perfectly reproducible and the pro= blem was solved by a change in the design of the fuel pressure regulator wi= th an update kit. I later changed to the stock Mazda fuel pressure regulat= or and that has worked fine also. It may also be useful to look at the effect of disconnecting the vacuum lin= e at idle. For my installation with the stock Mazda regulator, the fuel pr= essure 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 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. My system is 13B, stock red inj= ectors 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. --_000_3E8191F276108F4481AB0721BBA9269E05C4C8C2ponyexpressm10u_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

David,

It might be worthwhile to temporarily connect a mechanical gauge to the&= nbsp;pressurized section of the fuel system to verify that the fuel pr= essure sensing system is working correctly.

I have had a similar situation where the fuel pressure was lower after t= urning on the second HP pump and then the fuel pressure was highe= r again after turning off one of the pumps.  In my case, the problem w= as caused by an aftermarket adjustable pressure regulator that had excessive friction in a moving piston seal.  The p= ressures weren't perfectly reproducible and the problem was sol= ved by a change in the design of the fuel pressure regulator with an&n= bsp;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 vacu= um 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<= /a>, 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 pr= essure is 42 PSI on EM2, if I switch on the back-up pump with the primary p= ump 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 fro= m dynamic chamber.  Thanks,  David R. Cook  RV6A Rotary.

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