Message-Id: <5.1.1.5.2.20040525155725.0112fec8@localhost>
Date: Tue, 25 May 2004 16:08:01 -0500
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
From: Mark Steitle <msteitle@mail.utexas.edu>
Subject: Re: [FlyRotary] Re: Fuel Pump Design
In-Reply-To: <list-89626@logan.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed

Bill,
Yes, the regulator is mounted on the firewall and is located between the 
pumps/filters and fuel rail.  Also, there is a fuel return line off the 
regulator.

I actually had another option that I didn't list... #4 redesign my fuel 
delivery system to mimic the RV Otter.  If I understand Tracy's system 
(correct me if I'm wrong Tracy), it has a facet pump that transfers from 
one wing tank to the other (hooked to a 7 minute timer), and a high 
pressure pump on the other wing tank which delivers fuel to the fuel 
rail.  And finally a fuel return back to the second wing tank.  Nice thing 
here is it eliminates the need for a fuel selector valve.  It also locates 
the efi pump nearer the fuel source.

Mark S.  (I also like option #2)


  At 01:46 PM 5/25/2004 -0700, you wrote:

>Mark,
>
>I have worried about this also, but based on your description, I have a 
>question.
>
>It sounds like the line from the filters goes to the regulator, then back 
>to the valve. Does the regulator sit after the fuel rail? Or does the AN-6 
>line to the injector branch off from the regulator and 'dead end' at the 
>injectors? There is a fellow running an E-racer with the latter system 
>installed and it works fine, but his pumps are below the level of the fuel 
>tanks, at least 1 foot of head on the pumps.
>
>I think the small bypass hole sounds more reliable than a solenoid switch, 
>etc.
>
>Bill Schertz
>
>----------------------------------
>
>For the record, I have two of Tracy's efi pumps, with two efi filters, 
>hooked in parallel. They are mounted low on the fire wall. Upstream is a 
>gascolator and an Andair 6-port selector valve. Downstream of the 
>pumps/filters is a map sensing pressure regulator. There is a -6AN going 
>to the fuel rail, and a -4 return line back to the Andair valve/tank.
>
>I was curious if anyone else has had this happen and what they did to 
>resolve the issue. I have come up with two possible solutions.
>
>1. Tee off the pump output and put an electric solenoid valve in the line 
>and tee the outlet of the solenoid to the fuel return line, past the 
>regulator. Push-button switch on panel would activate the solenoid. If 
>needed, a second or two of activation should relieve the air-lock and 
>allow the pumps to re-prime.
>
>2. Install a bleed line around the pressure regulator with a small 
>metering orifice (.020-.030") that would bleed off any air that might get 
>trapped. (This appears to be the solution the Subaru group is focusing 
>on). This would be a full time bypass. This seems to be the simpler solution.
>
>3. Install a low pressure, high volume fuel pump in one, or both, of the 
>wing tanks. Procedure would be to always keep reserve fuel in this tank.
>
>Any comments from seasoned flyers would be welcomed.
>
>Mark S.