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From: "William" <wschertz@ispwest.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-967933@logan.com>
Subject: Re: [FlyRotary] Re: will EFI pumps pump air
Date: Mon, 30 May 2005 13:49:13 -0500
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One option, with the plumbing you and Rusty are trying, is to make the 
junction of the high pressure pump and the low pressure feed pump in a 
manner similiar to a 'water jet pump' or an 'aspirator' that uses a flowing 
liquid to pump another liquid or gas. Then the fact that the EFI pump is 
flowing hard becomes an advantage, helping the facet pump when it is turned 
on.

Word picture:
Envision a "T" fitting with the straight through section going from left to 
right, the T portion hanging down.  Fuel from the EFI pump enters from the 
left, and exits on the right, going back to the feed tank. Fuel from the 
Facet pump feeds into the arm of the T.

Modify the "T" fitting so that a slightly smaller tube that is inserted in 
the inlet side extends partway across the entry point of the arm. Now when 
fuel flows, a lower pressure point is generated at the exit of this smaller 
tube, that tends to pull fuel into the stream from the arm connection.

I have noticed this effect on just a straight 'unmodified' T, modifying it 
is truly 'experimental', but aspirators and jet pumps have a long history of 
working.

Bill Schertz
KIS Cruiser # 4045
----- Original Message ----- 
From: <ronmilligan@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, May 30, 2005 11:30 AM
Subject: [FlyRotary] Re: will EFI pumps pump air


> 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
>>
>>
>
>
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