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Fuel Flow Transducer-Injected
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alexpeterson(at)earthlink
Guest

Posted: Tue Apr 18, 2006 6:12 pm Post subject: Fuel Flow Transducer-Injected

 	  Quote: 	
		   

 

 First question, where's a good place to put this in the 

 stream of fuel?  I'm not too savvy on injected engines.  

 

 While talking with Electronics International today, I was 

 told that since there is a return of unused fuel, I'll need 

 TWO transducers and a little box that computes the unused 

 fuel.  This adds about $300 to the price of my fuel flow, and 

 am wondering if it's worth it now.  Thoughts?

 

 Paul Besing

 RV-4

 N73DD

 Arizona (For Now)


	


Paul, put it in the line between the servo and flow divider.  You'll have to

add a hose, and you may need to bring those lines back to the firewall.



For others paying attention, not all fuel injection systems have this return

line (Airflow Performance, for one), making the installation as simple as a

carb with respect to fuel lines.



Alex Peterson

RV6-A N66AP 751 hours, ripping out the Lasar system this weekend.

Maple Grove, MN

dan(at)rvproject.com
Guest

Posted: Tue Apr 18, 2006 6:17 pm Post subject: Fuel Flow Transducer-Injected

In the metered fuel line between the servo and flow divider is about as 

ideal a spot as any imho.



)_( Dan

RV-7 N714D

http://www.rvproject.com



---

dsvs(at)comcast.net
Guest

Posted: Tue Apr 18, 2006 7:05 pm Post subject: Fuel Flow Transducer-Injected

Paul,

The AFP has no return.  The purge valve is not used during noemal operations

and this is the only source of returned fuel.    Between the servo and the

flow divider is the best spot and I like Alex's idea of bringing thewe lines

to the firewall.  Don



--

dwight(at)openweave.org
Guest

Posted: Tue Apr 18, 2006 7:34 pm Post subject: Fuel Flow Transducer-Injected

On Tue Apr 18 22:10:46 2006, Alex Peterson wrote :

 	  Quote: 	
		  

> 

> First question, where's a good place to put this in the 

> stream of fuel?  I'm not too savvy on injected engines.  

> 

> While talking with Electronics International today, I was 

> told that since there is a return of unused fuel, I'll need 

> TWO transducers and a little box that computes the unused 

> fuel.  This adds about $300 to the price of my fuel flow, and 

> am wondering if it's worth it now.  Thoughts?

> 

> Paul Besing

> RV-4

> N73DD

> Arizona (For Now)



Paul, put it in the line between the servo and flow divider.  You'll have to

add a hose, and you may need to bring those lines back to the firewall.



For others paying attention, not all fuel injection systems have this return

line (Airflow Performance, for one), making the installation as simple as a

carb with respect to fuel lines.


	


According to the folks at Airflow Performance, Alex is right on the

money regarding where to install the transducer. I don't know what FI

system you are using, but with the API system there is no return line

for _normal_ operation. There is a return line for the purge valve 

but that is only used pre-start to purge vapor from the lines, and

at shutdown to _positively_ terminate fuel flow to the flow divider

(and thus insure a clean shutdown of the engine).



The API opinion on the amount of fuel returned is that it is so little

(startup and shutdown) that putting a Flowscan on the return line would

be of little benefit.



I learned all these little tidbits at the FI-101 class I took at the

API facility. If you really want to know about fuel injection basics

and are within striking distance of Spartanburg, SC ... I'd recommend

it highly. I'm not affiliated, but am a satisfied customer. 



Hope this helps.



  -- Dwight

pbesing(at)yahoo.com
Guest

Posted: Tue Apr 18, 2006 8:25 pm Post subject: Fuel Flow Transducer-Injected

Contrary to the fuel return on my airplane.  Not sure

what type of injection it is, but the fuel return is

substantial in flight.  I've run 30 mins on the left

tank, and after 30 mins on the right tank, the left

tank is full again.



Paul Besing



 	  Quote: 	
		   The API opinion on the amount of fuel returned is

 that it is so little

 (startup and shutdown) that putting a Flowscan on

 the return line would

 be of little benefit.

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Tue Apr 18, 2006 9:05 pm Post subject: Fuel Flow Transducer-Injected

I'm baffled why anyone would bother to run a return line on a Lycoming 

powered RV. Certificated aircraft with Lycomings don't use them and 

don't have problems. I fly behind an IO-360 without a return line over 

100 hours a year. The Bendix RSA injection systems aren't set up for a 

return line and don't need one. I don't know about non-certificated 

injection systems, but the Bendix system works damn well. I can run lean 

of peak no problem with stock injectors to as much as 70LOP. Starting 

cold or hot is simple, rarely any difficulty.

Do Not Archive

Paul Besing wrote:

 	  Quote: 	

 Contrary to the fuel return on my airplane.  Not sure

 what type of injection it is, but the fuel return is

 substantial in flight.  I've run 30 mins on the left

 tank, and after 30 mins on the right tank, the left

 tank is full again.

 Paul Besing

> The API opinion on the amount of fuel returned is

> that it is so little

> (startup and shutdown) that putting a Flowscan on

> the return line would

> be of little benefit.

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

stein(at)steinair.com
Guest

Posted: Tue Apr 18, 2006 9:22 pm Post subject: Fuel Flow Transducer-Injected

Wow! What kind of plumbing do you have that allows fuel to be ported back to

a tank that you're not drawing from?  Both the Bendix/Precision injection

systems shouldn't port fuel back to any tank during normal flight

operation....even with a purge valve (normally used only for starting and

shutdown) and most of us flying with the old antique Bendix/Precision FI's

don't even have a return line.  I know the subies and auto conversions are

different...but...I'm REALLY curious here...do tell!!



Cheers,

Stein.



do not archive



--

Bruce(at)glasair.org
Guest

Posted: Tue Apr 18, 2006 9:39 pm Post subject: Fuel Flow Transducer-Injected

A return line is to prevent vapor lock and it's a function of how tightly

your engine is cowled. More heat - more problems. So the need for a return

line would vary from airplane to airplane - not by engine/servo type. I have

an IO-540 AA1A5 in my Glasair III and I have a return line. My servo did not

come with one but it was easily added. Fuel stoppage can ruin your whole

day.



Bruce

www.glasair.org

 



--

Bob Barrow

Joined: 11 Jan 2006
Posts: 29

Posted: Wed Apr 19, 2006 2:23 am Post subject: Fuel Flow Transducer-Injected

Dan, I thought you put your fuel transducer just after the AFP boost pump on 

the cabin floor. Are you now unhappy with the results from that position.

[quote]From: "Dan Checkoway" <dan(at)rvproject.com>

Reply-To: rv-list(at)matronics.com

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

Subject: Re: Fuel Flow Transducer-Injected Date: Tue, 18 Apr 2006 

19:16:49 -0700






In the metered fuel line between the servo and flow divider is about as

ideal a spot as any imho.



)_( Dan

RV-7 N714D

http://www.rvproject.com



---

dan(at)rvproject.com
Guest

Posted: Wed Apr 19, 2006 5:03 am Post subject: Fuel Flow Transducer-Injected

 	  Quote: 	
		   Dan, I thought you put your fuel transducer just after the AFP boost pump 

 on

 the cabin floor. Are you now unhappy with the results from that position.


	


I did, and I don't have any problems.  But it's not the best location from a 

"scientific" standpoint.    Pressure drop across the transducer when it's 

on the suction side means more chances of vapor lock.  And why not put it 

where it "matters" most for accuracy?  In the metered fuel line is ideal 

from what I understand, since it's under positive pressure (as opposed to 

suction), and it's measuring the ACTUAL flow of fuel to the cylinders.



Just my 2 cents.



)_( Dan

RV-7 N714D

http://www.rvproject.com

phil(at)petrasoft.net
Guest

Posted: Wed Apr 19, 2006 6:12 am Post subject: Fuel Flow Transducer-Injected

I mounted mine in basically the same position that Dan did except that 

mine is further forward and attached to the floor.  I plan to move it 

this weekend to where Dan put his.  I think that the vibration on the 

floor is causing it to be WAY off.  It shows about 10% higher rate than 

what I am actually flowing and turning the boost pump on will give it 

another 10% on top of that.  With the airplane sitting in the hangar 

it's right on the money.

Dan,

How did you attach yours?  Is it bolted to something or is the tubing 

holding it?

Godspeed,

Phil Birkelbach - Houston Texas

RV-7 N727WB

http://www.myrv7.com

Dan Checkoway wrote:

 	  Quote: 	

>Dan, I thought you put your fuel transducer just after the AFP boost pump 

>on

>the cabin floor. Are you now unhappy with the results from that position.

>    

>

I did, and I don't have any problems.  But it's not the best location from a 

"scientific" standpoint.    Pressure drop across the transducer when it's 

on the suction side means more chances of vapor lock.  And why not put it 

where it "matters" most for accuracy?  In the metered fuel line is ideal 

from what I understand, since it's under positive pressure (as opposed to 

suction), and it's measuring the ACTUAL flow of fuel to the cylinders.

Just my 2 cents.

)_( Dan

RV-7 N714D

http://www.rvproject.com

pbesing(at)yahoo.com
Guest

Posted: Wed Apr 19, 2006 7:52 am Post subject: Fuel Flow Transducer-Injected

Dont' really know...I've got the cowl off right now

and it's kind of confusing...which is why I asked the

question in the first place...I know that some Cessnas

have this feature (it goes into a 3rd small storage

tank in the cowl) and bonanzas do as well.



So is it my understanding that I do not need this fuel

return?  Seems like an aweful lot of fuel to not

return (maybe 1 gallon per hour).  The plane was built

17 years ago, and has been that way ever since, with 5

owners, and no problems.



Paul Besing



--- Stein Bruch <stein(at)steinair.com> wrote:



[quote] 

 <stein(at)steinair.com>

 

 Wow! What kind of plumbing do you have that allows

 fuel to be ported back to

 a tank that you're not drawing from?  Both the

 Bendix/Precision injection

 systems shouldn't port fuel back to any tank during

 normal flight

 operation....even with a purge valve (normally used

 only for starting and

 shutdown) and most of us flying with the old antique

 Bendix/Precision FI's

 don't even have a return line.  I know the subies

 and auto conversions are

 different...but...I'm REALLY curious here...do

 tell!!

 

 Cheers,

 Stein.

 

 do not archive

 

 --

erichweaver(at)cox.net
Guest

Posted: Wed Apr 19, 2006 8:18 am Post subject: Fuel Flow Transducer-Injected

My io-360B1B (vertical induction) from Aerosport Power came with the purge valve installed adjacent to the flow divider.  I am tempted to remove it to avoid another fuel line and hole through the firewall, but havent yet.



I was a little surprised to see that everyone had installed the fuel flow transducer in front of the firewall.  Not that its bad mind you, just not where I installed mine.  Mine is aft of the firewall, between the boost pump and the firewall, where it seems to fit nicely under the cover plate. Now you are all messing with my head making me feel uncomfortable! Anything wrong with my location?



With the exception of the purge line, all the firewall forward fuel lines were pre-made, and supplied with my engine, so I didnt want to waste one of those by adding in the fuel transducer. Since I had to fabricate the fuel lines aft of the firewall anyway, it was an easy decision to put the transducer back there.



Whats really throwing me is that Dan Checkoway's web site  shows the transducer back by the fuel booster pump as well (see http://www.rvproject.com/20030520.html).  But I see Dan is now recommending the firewall forward location as well?  What gives?  Somebody is messin' wit my head.

klwerner(at)comcast.net
Guest

Posted: Wed Apr 19, 2006 8:25 am Post subject: Fuel Flow Transducer-Injected

Paul,

Would you have any pics on this installation of yours?  Like they say: A picture is worth 1000 words.

Konrad

  ---

dwight(at)openweave.org
Guest

Posted: Wed Apr 19, 2006 9:03 am Post subject: Fuel Flow Transducer-Injected

The one down-side to installing the transducer where Dan his his (and as you

noted he is now suggesting a new location too) is that it puts the transducer

on the suction-side of the engine driven fuel pump. The transducer acts as

a restriction in the line, and my understanding is that if you pull a fluid

through a restriction you will have a pressure drop across the restriction.



Given the rather low vapor pressure of avgas (or, gasoline in general) this

reduces your margin of protection against vapor lock in the feed lines. It

is possible (again, I am not an expert but am simply passing along some of

the things I learned in a fuel injection class) that on a really hot day 

vapor could form on the engine-side of the transducer as the engine driven

pump tries to pull fuel. This would be a "Bad Thing (tm)". 



Is this guaranteed to happen? No. Clearly many have flown with their fuel

flow transducers on the suction side of the fuel pump without incident. But

once the logic was outlined (and once some vapor pressure graphs were 

examined in detail) I have made the decision to install my transducer in

the line between the throttle-body and the flow divider. YMMV.



  -- Dwight



On Wed Apr 19 12:16:08 2006, erichweaver(at)cox.net wrote :

 	  Quote: 	
		  My io-360B1B (vertical induction) from Aerosport Power came with the purge valve installed adjacent to the flow divider.  I am tempted to remove it to avoid another fuel line and hole through the firewall, but havent yet.



I was a little surprised to see that everyone had installed the fuel flow transducer in front of the firewall.  Not that its bad mind you, just not where I installed mine.  Mine is aft of the firewall, between the boost pump and the firewall, where it seems to fit nicely under the cover plate. Now you are all messing with my head making me feel uncomfortable! Anything wrong with my location?



With the exception of the purge line, all the firewall forward fuel lines were pre-made, and supplied with my engine, so I didnt want to waste one of those by adding in the fuel transducer. Since I had to fabricate the fuel lines aft of the firewall anyway, it was an easy decision to put the transducer back there.



Whats really throwing me is that Dan Checkoway's web site  shows the transducer back by the fuel booster pump as well (see http://www.rvproject.com/20030520.html).  But I see Dan is now recommending the firewall forward location as well?  What gives?  Somebody is messin' wit my head.

Terry Watson

Joined: 09 Jan 2006
Posts: 290
Location: Seattle, WA USA

Posted: Wed Apr 19, 2006 9:03 am Post subject: Fuel Flow Transducer-Injected

Eric,



I too have an IO-360-B1B with Airflow Performance fuel injection. (You

didn't say who made the fuel injection, but I am assuming it is Airflow

Performance). There was some discussion on this list awhile back about this,

but the purge valve is apparently necessary to shut the engine down. The

engine shutdown checklist says to leave the mixture at full-rich and put the

purge valve control to off position.



Page 21 of my Airflow Performance manual says that when the mixture is at

idle cut-off, there is "approximately 1.0 to 3.0 pph leakage in this

position" which is apparently enough to keep the engine running.



Terry

RV-8A #80729 Baffles

Seattle

--

phil(at)petrasoft.net
Guest

Posted: Wed Apr 19, 2006 9:12 am Post subject: Fuel Flow Transducer-Injected

I think that all Dan is saying is that the "Theoretically Perfect" 

solution is between the servo and the flow divider, but there are more 

practical choices like putting it where you describe.  Mine is smack in 

the middle of the floor between the boost pump and the firewall.  It 

doesn't work very well and I'm gonna move it back to where Dan has his 

and see if that improves it any.  It think it's picking up vibration and 

it's causing high readings.  That floor shakes pretty good.



BTW you will love that purge valve.  I can start mine in two blades when 

it's heat soaked, and I like the idea of killing the engine with the 

purge valve instead of the mixture.  It will completely bleed off the 

fuel pressure, so that there is no way fuel can get into the cylinders 

while sitting on the ramp.  Seems much safer to me.  I'd suggest 

installing a spring to pull the purge valve closed in case the control 

cable breaks.  Also make sure that the control cable is of the locking 

variety and don't put it next to the cabin heat knob lest ye grab the 

wrong one whilst flying, and ruineth thy day.



Godspeed,



Phil Birkelbach - Houston Texas

RV-7 N727WB

http://www.myrv7.com



erichweaver(at)cox.net wrote:



 	  Quote: 	
		  



My io-360B1B (vertical induction) from Aerosport Power came with the purge valve installed adjacent to the flow divider.  I am tempted to remove it to avoid another fuel line and hole through the firewall, but havent yet.



I was a little surprised to see that everyone had installed the fuel flow transducer in front of the firewall.  Not that its bad mind you, just not where I installed mine.  Mine is aft of the firewall, between the boost pump and the firewall, where it seems to fit nicely under the cover plate. Now you are all messing with my head making me feel uncomfortable! Anything wrong with my location?



With the exception of the purge line, all the firewall forward fuel lines were pre-made, and supplied with my engine, so I didnt want to waste one of those by adding in the fuel transducer. Since I had to fabricate the fuel lines aft of the firewall anyway, it was an easy decision to put the transducer back there.



Whats really throwing me is that Dan Checkoway's web site  shows the transducer back by the fuel booster pump as well (see http://www.rvproject.com/20030520.html).  But I see Dan is now recommending the firewall forward location as well?  What gives?  Somebody is messin' wit my head.

dsvs(at)comcast.net
Guest

Posted: Wed Apr 19, 2006 9:38 am Post subject: Fuel Flow Transducer-Injected

-------------- Original message ----------------------

From: Phil Birkelbach <phil(at)petrasoft.net>

 	  Quote: 	

I just talked to the techs at Air Flow Performance.  They told me that the best place is between the servo and the purge valve.  They also said that  the transducer will work fine if you mount it vertically in that line.  They claim that they do it all the time.  I am going to try it that way and see how it works.  They also said to not mount it on the engine.  Don

 	  Quote: 	
		   I think that all Dan is saying is that the "Theoretically Perfect" 

 solution is between the servo and the flow divider, but there are more 

 practical choices like putting it where you describe.  Mine is smack in 

 the middle of the floor between the boost pump and the firewall.  It 

 doesn't work very well and I'm gonna move it back to where Dan has his 

 and see if that improves it any.  It think it's picking up vibration and 

 it's causing high readings.  That floor shakes pretty good.

 BTW you will love that purge valve.  I can start mine in two blades when 

 it's heat soaked, and I like the idea of killing the engine with the 

 purge valve instead of the mixture.  It will completely bleed off the 

 fuel pressure, so that there is no way fuel can get into the cylinders 

 while sitting on the ramp.  Seems much safer to me.  I'd suggest 

 installing a spring to pull the purge valve closed in case the control 

 cable breaks.  Also make sure that the control cable is of the locking 

 variety and don't put it next to the cabin heat knob lest ye grab the 

 wrong one whilst flying, and ruineth thy day.

 Godspeed,

 Phil Birkelbach - Houston Texas

 RV-7 N727WB

 http//www.myrv7.com

 erichweaver(at)cox.net wrote:

 >

 >

 >My io-360B1B (vertical induction) from Aerosport Power came with the purge 

 valve installed adjacent to the flow divider.  I am tempted to remove it to 

 avoid another fuel line and hole through the firewall, but havent yet.

 >

 >I was a little surprised to see that everyone had installed the fuel flow 

 transducer in front of the firewall.  Not that its bad mind you, just not where 

 I installed mine.  Mine is aft of the firewall, between the boost pump and the 

 firewall, where it seems to fit nicely under the cover plate. Now you are all 

 messing with my head making me feel uncomfortable! Anything wrong with my 

 location?

 >

 >With the exception of the purge line, all the firewall forward fuel lines were 

 pre-made, and supplied with my engine, so I didnt want to waste one of those by 

 adding in the fuel transducer. Since I had to fabricate the fuel lines aft of 

 the firewall anyway, it was an easy decision to put the transducer back there.

 >

 >Whats really throwing me is that Dan Checkoway's web site  shows the transducer 

 back by the fuel booster pump as well (see 

 http://www.rvproject.com/20030520.html).  But I see Dan is now recommending the 

 firewall forward location as well?  What gives?  Somebody is messin' wit my 

 head. 

 >

 >

 >

 >

 >

 >

 >

 > 

 > 

 > 

 >

 >

 >

 >  

 >

dan(at)rvproject.com
Guest

Posted: Wed Apr 19, 2006 10:44 am Post subject: Fuel Flow Transducer-Injected

 	  Quote: 	
		   How did you attach yours?  Is it bolted to something or is the tubing

 holding it?


	


It's resting on a silicone pad.  The tubing is somewhat rigid.  Mine is very 

accurate with the exception of when the boost pump is running.



)_( Dan

khorton01(at)rogers.com
Guest

Posted: Wed Apr 19, 2006 10:54 am Post subject: Fuel Flow Transducer-Injected

On 19 Apr 2006, at 11:52, Paul Besing wrote:



 	  Quote: 	
		   



 Dont' really know...I've got the cowl off right now

 and it's kind of confusing...which is why I asked the

 question in the first place...I know that some Cessnas

 have this feature (it goes into a 3rd small storage

 tank in the cowl) and bonanzas do as well.



 So is it my understanding that I do not need this fuel

 return?  Seems like an aweful lot of fuel to not

 return (maybe 1 gallon per hour).  The plane was built

 17 years ago, and has been that way ever since, with 5

 owners, and no problems.


	


Where is that fuel return line coming from?



If it is coming from the fuel injection servo, which make and model  

servo is it?



It may be coming from a pressure regulating valve that is part of the  

high pressure fuel pump.  If that is the case, most people run the  

fuel return into a T in the fuel line from the fuel selector valve.   

A small number of people use an expensive fuel selector from Andair  

that has two valves controlled by one knob.  That allows you to send  

the return fuel to whatever tank is currently providing fuel, which  

avoids the problem of over filling a tank with the return fuel.



Kevin Horton         RV-8 (finishing kit)

Ottawa, Canada

http://www.kilohotel.com/rv8

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