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From: <ronmilligan@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: will EFI pumps pump air
Date: Mon, 30 May 2005 12:30:27 -0400
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Rusty,

I copied your system in doing mine.  I asked about the facet over coming the pressure from the returning fuel line.  I wish you would have tested yours more before I finished mine.  Would it be possible to put a larger diameter return line from where the facet pump line joins the return line?  I'm a long way from testing mine so when you find a solution let us know.

Ron Milligan
RV7 QB FUSE
Aliso Viejo CA (Temp: Balad, Iraq)

> 
> From: "Russell Duffy" <13brv3@bellsouth.net>
> Date: 2005/05/30 Mon AM 11:51:53 EDT
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: will EFI pumps pump air
> 
> 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  
> 
>