Fuel is gravity routed from tanks to ganged fuel selector out to T-fitting with each pump on the sides of the T,  to another T,  into main line out to eng., pressure sender is mounted directly after the T  where the two pumps come together.   All this is in front of the wing spar near the floor in an RV6A. This would make the pumps in parallel & the pressure is the same from either pump, but both together pressure drops.   David 

---

From: "Mark Steitle" msteitle@gmail.com
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, June 13, 2012 8:36:19 AM
Subject: [FlyRotary] Re: Fuel presure question.

David,

How are your pumps plumbed... in parallel or series?  What kind of
pressure do you get when running the backup pump only?

Mark

On 6/13/12, Tracy <rwstracy@gmail.com> wrote:
> Hmmmm...  Mine goes up about a pound when I switch on the second pump.  What
> happens when you turn both off?
>
> Tracy
>
> Sent from my iPad
>
> On Jun 12, 2012, at 7:11 PM, hoursaway1@comcast.net wrote:
>
>> Question about fuel pressure indications, at fast idle 2200 RPM, fuel
>> pressure is 42 PSI on EM2, if I switch on the back-up pump with the
>> primary pump the pressure drops to 35 PSI, can here both pumps running, if
>> I switch off either pump pressure goes back to 42 PSI.  My system is 13B,
>> stock red injectors all four, pressure regulator is stock Mazda on the end
>> of fuel rail with vacume connection from dynamic chamber.  Thanks,  David
>> R. Cook  RV6A Rotary.
>

--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html