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912ULS fuel return line orifice size

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peterz(at)zutrasoft.com
Guest

Posted: Fri Dec 04, 2020 4:40 am Post subject: 912ULS fuel return line orifice size

Hi Folks,

I'm currently re-doing my fuel lines and configuration and have discovered my return orifice was made at 1/32" or 0.68mm which is twice the size of the spec'd rotax 0.33 mm or 1/64".  It may explain why whenever I turned the electric pump off the pressure would drop to near zero for a couple seconds before recovering to the expected 4-5psi.





Curious what size other folks are running? 0.33mm?

Cheers and thanks,

Pete Z.

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brian.davies44(at)gmail.c
Guest

Posted: Fri Dec 04, 2020 5:22 am Post subject: 912ULS fuel return line orifice size

Hi Pete

If you are running the latest mechanical fuel pump I think you will find that Rotax have published information that states a brief drop in fuel pressure is “normal”.  I have never understood why this should be “normal” but…

 

I don’t think it is linked to the size of the return line orifice.

 

Regards

 

Brian

 

From: owner-europa-list-server(at)matronics.com <owner-europa-list-server(at)matronics.com> On Behalf Of Pete Zut

Sent: 04 December 2020 12:40

To: europa-list <europa-list(at)matronics.com>

Subject: 912ULS fuel return line orifice size



 

Hi Folks,



 



I'm currently re-doing my fuel lines and configuration and have discovered my return orifice was made at 1/32" or 0.68mm which is twice the size of the spec'd rotax 0.33 mm or 1/64".  It may explain why whenever I turned the electric pump off the pressure would drop to near zero for a couple seconds before recovering to the expected 4-5psi.



 



 



Curious what size other folks are running? 0.33mm?



 



Cheers and thanks,



Pete Z.



 

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peterz(at)zutrasoft.com
Guest

Posted: Fri Dec 04, 2020 5:48 am Post subject: 912ULS fuel return line orifice size

Many thanks Brian for the info..... I'm relieved to hear that others are

seeing the same, and that Rotax actually published something on it.

Cheers and blue skies 

(and I'm leaving the orifice as per the Europa size)



On Fri, Dec 4, 2020 at 8:30 AM Brian Davies <brian.davies44(at)gmail.com>

wrote:



[quote] Hi Pete



 If you are running the latest mechanical fuel pump I think you will find

 that Rotax have published information that states a brief drop in fuel

 pressure is “normal”.  I have never understood why this should be “normal”

 but…



 I don’t think it is linked to the size of the return line orifice

- The Matronics Europa-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List

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