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Date: Mon, 30 May 2005 10:51:19 -0600
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: will EFI pumps pump air
Message-Id: <20050530105119.78f5aaf8.bob@bob-white.com>
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I'm 'T'ing the output of the transfer pump into the supply line from
the main tank before the gascolator.  The transfer pump will only have
to overcome the head of the fuel, about 3 feet or so to push fuel back
into the main tank.  Is there anything I'm missing that would keep this
from working?

Bob W.

On Mon, 30 May 2005 10:51:53 -0500
"Russell Duffy" <13brv3@bellsouth.net> wrote:

> Will the EFI pump move enough air through it to disturb the fuel rail
> pressure that's being delivered from the other pump,  
>  I would say yes  
>  
>  
> I'd bet that you have a 50-50 chance of being right :-)   Seriously, I'm not
> so sure it would pump air well enough to overcome the 43 psi of pressure
> that the other pump is putting in the rail.  I guess the only way to find
> out it to do the experiment. I'm not completely sure that's what I want to
> do anyway.  
>  
> Yep, still trying to figure out how to fix my fuel transfer system.   
>  What's it look like now? 
>  
>  
> Remember the recent caution about copying a system 100%, or it becomes a new
> system?  Well, guilty as charged.  My system is just like Tracy's, except
> that I only have one return line to my feed tank.   I plumbed the wimpy
> facet transfer pump into the same line that returns from the regulator.
> That means the facet pump is trying to push against the return flow from the
> regulator, and it's not doing too well.  
>  
> Even at it's best, on the ground, with no other pumps on, the facet is slow.
> In the air, fighting against one EFI pump's return flow, it takes a long
> long time to see fuel moving.  With both EFI pumps on, I almost wonder if
> fuel isn't going backwards into the non-feed tank anytime the facet wasn't
> on because the check ball isn't perfect.  I added a one way valve to stop
> this, and to stop the fuel from leveling itself between tanks when parked.
> 
>  
> The obvious solution is to "simply" (NOT) add another hose to the feed tank.
> Even if I go through all that hassle, I'm still stuck with the slow rate of
> transfer of the facet.  It's probably still the best option, but I'm going
> to investigate every other option before doing this.  
>  
>  Rusty  
> 


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