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Rotax 912ULS / Fuel Pump Setup

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Martin Pohl

Joined: 30 Jan 2006
Posts: 118
Location: CH-8645 Jona SG, Switzerland

Posted: Sun Jul 01, 2007 1:56 am Post subject: Rotax 912ULS / Fuel Pump Setup

Hi folks



(1) My Zodiac-drawing shows that the elec aux fuel pump (Facet) shall be installed in parallel to the mechanical fuel pump.

(2) There is a fuel filter upstream of the mechanical fuel pump and a fuel filter downstream of the elec fuel pump. Any idea why that is (down- resp. upstream)?



Rotax emailed me that the elec aux fuel pump is normally installed in series with the mechanical fuel pump. Somehow I like the idea of a parallel setup (no additional pressure rise due to elec pump, more redundancy in case of fuel pump blockage). Any comments?



Does the normal facet pump works as a check valve if not running (in other direction than normal flow)?



Does anybody use the newer POSI-FLOW pumps? They are smaller and seem to be quieter than the normal facet pump. Facet states that they are the replacement for the well-known qube facet pumps.



Cheers

Martin

Zodiac CH601XL HB-YNA

_________________
Martin Pohl
Zodiac XL QBK
8645 Jona, Switzerland
http://www.pohltec.ch/ZodiacXL/Main.html

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Jul 01, 2007 6:45 am Post subject: Re: Rotax 912ULS / Fuel Pump Setup

Hi Martin,



You can run the pump parallel or in line and it would work. I think most have it installed in line. One or two fuel filters will work. Looks like someone wanted to make sure the electric pump was filtered before fuel went through it.  

The Facet pump will not cause any flow problems, even when turned off.  I only ran my aux. electric pump at start up then turned it off, no need for it. Quite a few aircraft with the 912 don't have electric aux. pumps, just the mechanical one on the engine. 

I turned it on before the engine start to help prime the fuel system and to listen to see if it was working. After start up I turned it off. It was only there in case the mechanical one failed. If the mechanical one failed hitting the aux. pump switch and a restart was easy and quick. There was a fuel pump recall here not too long ago and it is still going on to replace the mechanical fuel pumps in part because the people that ran an electric fuel pump up stream of the mecahanical one caused problems at the carb, it over pressured.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

pwmac(at)sisna.com
Guest

Posted: Sun Jul 01, 2007 7:44 am Post subject: Rotax 912ULS / Fuel Pump Setup

Facet is normally used in series. It has a check valve built in. 

Filters always go upstream of the Facet. Use a big replaceable one, 

preferably for AN style fittings so you don't have to cut hoses to do 

maintenance. I read several places that the Facet does not have the 

check valve, but it really does. I have a hard time seeing why a 

parallel connection is desired. Maybe Zodiac thinks the stock pump 

will fail closed?

A filter downstream of the pumps is a pressure reducer and probably 

not necessary since unwanted stuff created by of either pumps is 

pretty unlikely.



Have you asked Zodiac if they have an updated schematic? Sometimes 

manufactures learn by experience.



Posi-flow would be an experiment. Facet would be the standard.

Paul

=======================

At 03:56 AM 7/1/2007, you wrote:

 	  Quote: 	
		  



Hi folks



(1) My Zodiac-drawing shows that the elec aux fuel pump (Facet) 

shall be installed in parallel to the mechanical fuel pump.

(2) There is a fuel filter upstream of the mechanical fuel pump and 

a fuel filter downstream of the elec fuel pump. Any idea why that is 

(down- resp. upstream)?



Rotax emailed me that the elec aux fuel pump is normally installed 

in series with the mechanical fuel pump. Somehow I like the idea of 

a parallel setup (no additional pressure rise due to elec pump, more 

redundancy in case of fuel pump blockage). Any comments?



Does the normal facet pump works as a check valve if not running (in 

other direction than normal flow)?



Does anybody use the newer POSI-FLOW pumps? They are smaller and 

seem to be quieter than the normal facet pump. Facet states that 

they are the replacement for the well-known qube facet pumps.



Cheers

Martin

Zodiac CH601XL HB-YNA



--------

Martin Pohl

Zodiac XL QBK

8645 Jona, Switzerland

www.pohltec.ch/ZodiacXL





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=121499#121499

jack.kuehn(at)gmail.com
Guest

Posted: Sun Jul 01, 2007 10:17 am Post subject: Rotax 912ULS / Fuel Pump Setup

Martin,

I run a facet pump in series, and the literature that came with the pump 

said a filter before the pump is mandatory, and one is made to screw 

right into it.  It's cheap and works fine.  Personally I like the noisy 

pump because I can hear it when it is on, just barely, over the engine 

noise, so I do not forget to turn it off!  Though you are right, it does 

run the pressure up to near the maximum allowed for the carbs on my 912 

UL.  I have not had a problem with this in 115 hours.  How does the 

parallel setup work?  Is there a check valve involved?  The facet pump I 

have does not act as a check valve. 



Jack



Martin Pohl wrote:

 	  Quote: 	
		   



 Hi folks



 (1) My Zodiac-drawing shows that the elec aux fuel pump (Facet) shall be installed in parallel to the mechanical fuel pump.

 (2) There is a fuel filter upstream of the mechanical fuel pump and a fuel filter downstream of the elec fuel pump. Any idea why that is (down- resp. upstream)?



 Rotax emailed me that the elec aux fuel pump is normally installed in series with the mechanical fuel pump. Somehow I like the idea of a parallel setup (no additional pressure rise due to elec pump, more redundancy in case of fuel pump blockage). Any comments?



 Does the normal facet pump works as a check valve if not running (in other direction than normal flow)?



 Does anybody use the newer POSI-FLOW pumps? They are smaller and seem to be quieter than the normal facet pump. Facet states that they are the replacement for the well-known qube facet pumps.



 Cheers

 Martin

 Zodiac CH601XL HB-YNA



 --------

 Martin Pohl

 Zodiac XL QBK

 8645 Jona, Switzerland

 www.pohltec.ch/ZodiacXL





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=121499#121499



   


	


http://mountaintime.myrf.net/imglib/index.htm

hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Sun Jul 01, 2007 1:24 pm Post subject: Rotax 912ULS / Fuel Pump Setup

Martin:



The info I hear is that make sure you use the "E" series Facet pump. The

pumps that are not the newer "E" series are evidently older pumps (prior to

2001) and have had up to 10% failure rates. These older pumps are evidently

still being sold until the inventory is exhausted. I suggest that you try to

get the newer "E" series.



Hugh Mckay



--

Martin Pohl

Joined: 30 Jan 2006
Posts: 118
Location: CH-8645 Jona SG, Switzerland

Posted: Sun Jul 01, 2007 1:32 pm Post subject: Re: Rotax 912ULS / Fuel Pump Setup

Thank you for all your helpful information! I will ask Zenith about their actual opinion about fuel pump installation.



Do you have a good source for fuel filters (what and where to buy)? I heard about fuel filters that have a mesh that is too narrow and might clog too quickly. What mesh size is apopropriate for the fuel filters?



Cheers

Martin

_________________
Martin Pohl
Zodiac XL QBK
8645 Jona, Switzerland
http://www.pohltec.ch/ZodiacXL/Main.html

mpetersen(at)repsol.com.a
Guest

Posted: Sun Jul 01, 2007 2:58 pm Post subject: Rotax 912ULS / Fuel Pump Setup

G'day Martin,



One of the reasons why you hear many different stories about "Facet fuel

pumps" is that there are literally many different pumps available. Check

the link below to choose the right pump, pressure, with or without a

check valve, anti-siphon valve, etc, etc, as required. There are pumps

that run at low pressure (3-4psi) that are under the maximum nominated

in the Rotax Installation Manual (4 or 5 psi, I think ????). Your final

setup, parallel or in series, will determine whether you need the check

valve or not. For example, most people who run a cube pump in series,

just in case of a mechanical pump failure, run a pump without a check

valve or anti-siphon valve so in case of a Facet pump failure there is

no (or very little) restriction in flow to contend with.



http://www.facet-purolator.com/solidstate.asp



The filter that is recommended on the fitting instructions that come

with the cube type pump, screws directly into the pump (Part no 479735),

are 74 micron and they are available from Aircraft Spruce for $3.40

each.



Like most of these questions, the answer results in many more questions,

but I hope this helps.



Good luck,



Michael.

Sydney, Australia.





--

rampil

Joined: 04 May 2007
Posts: 870

Posted: Tue Jul 03, 2007 5:34 am Post subject: Re: Rotax 912ULS / Fuel Pump Setup

Martin,



Since Zodiac is the odd man out here (almost all facet pumps are serial in

Rotax systems) why don't you ask them for their rationale?  If they

answer, please let us know. Thanks,

_________________
Ira N224XS

Martin Pohl

Joined: 30 Jan 2006
Posts: 118
Location: CH-8645 Jona SG, Switzerland

Posted: Sun Jul 08, 2007 11:21 am Post subject: Re: Rotax 912ULS / Fuel Pump Setup

Answer from Zenith:



One reason is for the second pump to by-pass the first in case of failure in one.



Cheers Martin

_________________
Martin Pohl
Zodiac XL QBK
8645 Jona, Switzerland
http://www.pohltec.ch/ZodiacXL/Main.html

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Jul 08, 2007 11:27 am Post subject: Re: Rotax 912ULS / Fuel Pump Setup

Hi Martin,



When these pumps fail they tend to fail open. Either pump can pass fuel through the other without any problem.

Your Zodiac has fuel in the wings, correct?

If it does, and if the mechanical Rotax pump failed it is set to fail open and fuel will bypass the pump. You may not get full rpm and fuel pressure, but you will be able to fly. The guys with low fuel tanks have a problem.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

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