: -------------- The Facet pump in this position is a two edged sword. It can help eliminate a vapor lock when on but it is a restriction that can create a vapor lock when off. A properly laid out fuel system should not require another pump to prime the main EFI pump. It is a bandaid IMO. Again, any restriction other than a strainer to stop the 'big chunks' before the EFI pumps is not a good thing. Tracy No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005 --NextPart_Webmail_9m3u9jl4l_16496_1108660995_1 Content-Type: text/html Content-Transfer-Encoding: 8bit

Paul,

That is a long round about trip with relatively low head pressure for the fuel !!

I would think the boost pump (If even necessary + somewhat restrictive) should

be positioned close to the fuel tank outlet and be pushing rather than pulling

fuel from tanks to fuel selector to sump . Again it is not clear to me if you feed

fuel from both tanks at once or select a tank at the fuel valve . If you select tanks

then to do as I just suggested would require a boost pump for each tank in order

to keep them close to tank outlet.......FWIW

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Paul" <sqpilot@bellsouth.net>: --------------

Hi, Kelly....the efi pumps are the last item before the fuel rail and fuel pressure regulator. Here is the basic system... The fuel in the main tanks goes downhill to the fuel selector. Fuel then goes downhill again through the Facet pump into the top of the sump tank. Fuel then comes out of the bottom of the sump tank through the gascolator into the EFI pump(s), then to the fuel rail with fuel pressure regulator attached, then that returned fuel goes back into the top of the sump tank. That is the complete system. Take care. Paul Conner

----- Original Message -----

From: Kelly Troyer

To: Rotary motors in aircraft

Sent: Thursday, February 17, 2005 12:36 AM

Subject: [FlyRotary] Re: Vapor Lock

Paul,

I have forgotton your exact fuel system layout.......Do your efi pumps push

fuel from sump tank to fuel valve then to engine or are they installed after the

fuel valve and suck fuel from all the way back to the sump tank ? I tend to

agree with Tracy and others that the Facet boost pump is a restriction.....Have

you tried removing it and heating the engine as in previous tests to see if

you get a vapor lock ?

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Tracy Crook" <lors01@msn.com>: --------------

The Facet pump in this position is a two edged sword. It can help eliminate a vapor lock when on but it is a restriction that can create a vapor lock when off. A properly laid out fuel system should not require another pump to prime the main EFI pump. It is a bandaid IMO. Again, any restriction other than a strainer to stop the 'big chunks' before the EFI pumps is not a good thing.

Tracy

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Checked by AVG Anti-Virus.
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