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Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Sat Aug 15, 2009 12:25 pm Post subject: Fuel Flow variations

Is anyone experiencing variations in fuel flow readings?

I am experiencing variations in fuel flow readings of up to .5 gph.  

Typically the variations are .1-.3 gph. I've got the flow meter mounted 

in the tunnel per Van's plans. And after talking to Don Rivera (at) Airflow 

Performance, he believes that the variations are due to the location of 

the meter. Apparently the optimum location is between the servo and the 

distribution spider. I've searched the archives, as I recalled some 

dialogue on this subject and basically verified what Don said about 

mounting location.

I'm interested to know if others are experiencing similar readings and 

any attempts to improve or correct the situation.



Thanks



Deems Davis N519PJ

http://deemsrv10.com/

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Sat Aug 15, 2009 1:13 pm Post subject: Fuel Flow variations

There are differing opinions as to where it should go. The problem with putting it in the line to the spider is that line normally is mostly vertical, and there is very little horizontal line to insert the sender.  EI, which I think  uses the same sender recommends between the mechanical fuel pump and the fuel servo, unless it is a Continental time injection that returns fuel to the tank full time. It comes down to where it will conveniently fit, and have a straight, horizontal line/hose for several inches before the sending unit.

 .1-.2 gph fluctuation is pretty normal, more than that may be a problem. The connections between the sending unit and the instrument can be an issue.



On Sat, Aug 15, 2009 at 1:24 PM, Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)> wrote:

 [quote]--> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)>

  

 Is anyone experiencing variations in fuel flow readings?

 I am experiencing variations in fuel flow readings of up to .5 gph.  Typically the variations are .1-.3 gph. I've got the flow meter mounted in the tunnel per Van's plans. And after talking to Don Rivera (at) Airflow Performance, he believes that the variations are due to the location of the meter. Apparently the optimum location is between the servo and the distribution spider. I've searched the archives, as I recalled some dialogue on this subject and basically verified what Don said about mounting location.

  I'm interested to know if others are experiencing similar readings and any attempts to improve or correct the situation.

 

 Thanks

 

 Deems Davis N519PJ

 http://deemsrv10.com/

 

 

 ===========

 arget="_blank">http://www.matronics.com/Navigator?RV10-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

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

rv(at)thelefflers.com
Guest

Posted: Sat Aug 15, 2009 1:15 pm Post subject: Fuel Flow variations

Deems, good timing on your question.  Ivan Kristensen and I were having the

same discussion the other day.   We too would like to hear from anyone that

mounted there fuel flow sensor in a non-standard location to minimize the

impact of when the fuel pump is engaged.



My memory seems to think that Gary B. may have done this and may have some

data since he's flying now.



Thanks,



Bob

#40684



--

dlm46007(at)cox.net
Guest

Posted: Sat Aug 15, 2009 1:15 pm Post subject: Fuel Flow variations

I think you need to put things in perspective. Everyone thinks that if you

have a digital reading that's the last word. It used to be analog needles

and a printed scale on the dial. Fluctuations occurred all the time but

measurements were not precise enough to matter or be discernible. A variety

of things including varying temps or pressures can cause a sensor to output

differently. We are measuring milli and micro values of electricity. It is

quite possible that the fluctuations are within the accuracy of the sensor

but the measurement of the volt or pressure or gph on a digital gauge

pretends to be more precise. That said: my fuel flow bounces around by .1 to

.3 with the engine driven pump. Turn on the boost pump and see the same

mixture setting show many gallons more flow.



--

wcurtis(at)nerv10.com
Guest

Posted: Sat Aug 15, 2009 1:24 pm Post subject: Fuel Flow variations

Yes, this is the consensus of AFS, EI, Airflow et al.  For this reason as well as easier access to the transducer, I have moved my fuel flow transducer from the tunnel to the servo output port.  With some additional parts from AN Plumbing, I was able to put it there without any change to the hoses.

   

 William

 http://wcurtis.nerv10.com/

 



 

 On Sat, Aug 15, 2009 at 4:24 PM, Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)> wrote:

 [quote]--> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net (deemsdavis(at)cox.net)>

 

Is anyone experiencing variations in fuel flow readings?

I am experiencing variations in fuel flow readings of up to .5 gph.  Typically the variations are .1-.3 gph. I've got the flow meter mounted in the tunnel per Van's plans. And after talking to Don Rivera (at) Airflow Performance, he believes that the variations are due to the location of the meter. Apparently the optimum location is between the servo and the distribution spider. I've searched the archives, as I recalled some dialogue on this subject and basically verified what Don said about mounting location.

 I'm interested to know if others are experiencing similar readings and any attempts to improve or correct the situation.



Thanks



Deems Davis N519PJ

http://deemsrv10.com/

 br> www.matronics.com/Navigator?RV10-List" target="_blank">http://www.matronics.com/Navigator?RV10-List

 ronics.com/" target="_blank">http://forums.matronics.com

 Matt Dralle, List Admin.

 =====





[b]

orchidman

Joined: 10 Jul 2006
Posts: 277
Location: Oklahoma City - KRCE

Posted: Sat Aug 15, 2009 1:38 pm Post subject: Re: Fuel Flow variations

I have no problems following AFS's recommendations as others here have also noted.  The engine shop provided me with the new hoses.

100_3207.JPG

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_________________
Gary Blankenbiller
RV10 - # 40674
(N2GB Flying)

speckter(at)comcast.net
Guest

Posted: Sat Aug 15, 2009 3:29 pm Post subject: Fuel Flow variations

I too get variations using the stock location.  In a previous aircraft I had

it located between the servo and the spider with good success, but as

pointed out, I did not have digital readout on it.  I am tempted to move

mine, but would really like to get input from those who have found a rock

steady location.



Gary Specketer



--

rbibb

Joined: 16 Jul 2009
Posts: 37

Posted: Sat Aug 15, 2009 4:03 pm Post subject: Fuel Flow variations

On the Matronics web site Matt used to sell a small spherical device to put

in the line to dampen out pulsations to improve accuracy or minimize

disturbances.  Sort of like a "water hammer" shock absorber put in your

water line at home.



Might be worth a try...



See:  http://www.matronics.com/fuelchec/dampener.html

Richard Bibb

972-771-2598

972-835-5979 mobile

 

 

--

rv(at)thelefflers.com
Guest

Posted: Sat Aug 15, 2009 4:04 pm Post subject: Fuel Flow variations

I found photo's of Rob Hickman's installation:



http://lh6.ggpht.com/RobHickmanAFS/SNltW4FJUII/AAAAAAAAAQo/sX7EW06y0Zg/s800/

Fuel%20Flow%20Transducer.jpg



Gary Blankenbiller's at:



http://www.wingscc.com/n2gb/FF1-Engine/100_3207.jpg



Looking at the install procedures for the EI FT-60 on EI's site (which is

used by several of the EFIS vendors):



1. Find a convenient location between the Fuel Servo and Flow

Divider and away from any hot exhaust pipes to suspend the

Fuel Flow Transducer





--

dave.saylor.aircrafters(a
Guest

Posted: Sat Aug 15, 2009 4:35 pm Post subject: Fuel Flow variations

FF is definitely more stable measured between the servo and the spider.  I moved my sender because of the erroneous reading with the boost pump on, and I'm happy with the results.  I do see very minor fluctuations now and then, but I suspect that with an analog instrument, you would never notice.  It's just that digital instruments are so...digital.

 

On Sat, Aug 15, 2009 at 4:25 PM, gary <speckter(at)comcast.net (speckter(at)comcast.net)> wrote:

[quote] --> RV10-List message posted by: "gary" <speckter(at)comcast.net (speckter(at)comcast.net)>

 

 I too get variations using the stock location.  In a previous aircraft I had

 it located between the servo and the spider with good success, but as

 pointed out, I did not have digital readout on it.  I am tempted to move

 mine, but would really like to get input from those who have found a rock

 steady location.

 

 Gary Specketer

 

 --

AV8ORJWC

Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"

Posted: Sun Aug 16, 2009 8:49 am Post subject: Fuel Flow variations

Matt Dralle offered a small but well built fluid accumulator which can

assist the dampening pressure fluctuations of pump actions.  If the

accumulator is used and placed prior to the sensor the degree of

fluctuation should be reduced at the point of indication.

John

#40600



--

rv10builder(at)verizon.ne
Guest

Posted: Sun Aug 16, 2009 10:50 am Post subject: Fuel Flow variations

I agree there is a proven improvement with the forward location and with 

Matt's ball (which btw would never fit for me in my limited space) however I 

remind the group the flip side to this. A while back Tim Olson and the 

Grumpy General, two people I respect, mentioned that there is a  brief time 

the pump is actually even on, take off and landing. The time it actually 

caused an issue was rather brief and played a minor issue in the total 

scheme of things.

 	  Quote: 	
		  From a part of the e-mail by Tim, written last January- " While I do see the 

increase in fuel flow, just like you do, with mine installed in the stock 
	


location, it doesn't cause me any headaches.  I only use the fuel boost for 

maybe 60 seconds during takeoff, and even on landing if I do, it's only for 

about 60 seconds again....just that timeframe that I'm under about 500' AGL 

If you only use it a couple minutes during the flight, it won't change those 

readings much at all. I've consistently been accurate to within about .1-.2 

gallons over a 40-45 gallon flight, so it's just not worth worrying about. 

In over 400 hours I've never had a fuel fill up that had any noticeable 

amount of difference over what the totalizer  told me I should be adding."

By all means consider moving the location to the front, especially if you 

haven't done the install already per the plans, but for those who already 

have the sensor in place, think about this before you make a modification 

from the Van's plans- new hoses?, new setups?.. ask yourself with this 

information if it's worth the effort?

Just bringing a difference perspective for anyone who worried about this, as 

I did initially.



Tim may have changed his mind on this, if so Tim please advise.



Pascal

#40720

--------------------------------------------------

From: "John Cox" <johnwcox(at)pacificnw.com>

Sent: Sunday, August 16, 2009 9:45 AM

To: <rv10-list(at)matronics.com>

Subject: RE: Fuel Flow variations



[quote] 



 Matt Dralle offered a small but well built fluid accumulator which can

 assist the dampening pressure fluctuations of pump actions.  If the

 accumulator is used and placed prior to the sensor the degree of

 fluctuation should be reduced at the point of indication.

 John

 #40600



 --

Tim Olson

Joined: 25 Jan 2007
Posts: 2882

Posted: Sun Aug 16, 2009 11:20 am Post subject: Fuel Flow variations

Nope, I'm still very happy.  As far as access to the sender goes, I've  

never had reason to touch it since it was first wired in.  It works  

plenty well for me and I can usually plan on the reading being dead on  

when I refuel.

Tim

On Aug 16, 2009, at 11:44 AM, "Pascal" <rv10builder(at)verizon.net> wrote:

[quote] 

 I agree there is a proven improvement with the forward location and  

 with Matt's ball (which btw would never fit for me in my limited  

 space) however I remind the group the flip side to this. A while  

 back Tim Olson and the Grumpy General, two people I respect,  

 mentioned that there is a  brief time the pump is actually even on,  

 take off and landing. The time it actually caused an issue was  

 rather brief and played a minor issue in the total scheme of things.

> From a part of the e-mail by Tim, written last January- " While I  

> do see the

 increase in fuel flow, just like you do, with mine installed in the  

 stock location, it doesn't cause me any headaches.  I only use the  

 fuel boost for maybe 60 seconds during takeoff, and even on landing  

 if I do, it's only for about 60 seconds again....just that timeframe  

 that I'm under about 500' AGL If you only use it a couple minutes  

 during the flight, it won't change those readings much at all. I've  

 consistently been accurate to within about .1-.2 gallons over a  

 40-45 gallon flight, so it's just not worth worrying about. In over  

 400 hours I've never had a fuel fill up that had any noticeable  

 amount of difference over what the totalizer  told me I should be  

 adding."

 By all means consider moving the location to the front, especially  

 if you haven't done the install already per the plans, but for those  

 who already have the sensor in place, think about this before you  

 make a modification from the Van's plans- new hoses?, new setups?..  

 ask yourself with this information if it's worth the effort?

 Just bringing a difference perspective for anyone who worried about  

 this, as I did initially.

 Tim may have changed his mind on this, if so Tim please advise.

 Pascal

 #40720

 --------------------------------------------------

 From: "John Cox" <johnwcox(at)pacificnw.com>

 Sent: Sunday, August 16, 2009 9:45 AM

 To: <rv10-list(at)matronics.com>

 Subject: RE: Fuel Flow variations

> 

>

> Matt Dralle offered a small but well built fluid accumulator which  

> can

> assist the dampening pressure fluctuations of pump actions.  If the

> accumulator is used and placed prior to the sensor the degree of

> fluctuation should be reduced at the point of indication.

> John

> #40600

>

> --

speckter(at)comcast.net
Guest

Posted: Sun Aug 16, 2009 3:14 pm Post subject: Fuel Flow variations

I notice fluctuations while I am trying to adjust LOP.  Like Tim, I can live

with the change during the operation of the boost pump, but the LOP

adjustment is more irritating.



Gary Specketer



--

gengrumpy(at)aol.com
Guest

Posted: Sun Aug 16, 2009 3:41 pm Post subject: Fuel Flow variations

Same for me.



And on hot days if the engine driven pump pressure falls too low, I  

use the electric fuel pump to keep the pressure up until I get to  

altitude.



Totalizer and fuel used consistently accurate.



grumpy

N184JM



On Aug 16, 2009, at 2:18 PM, Tim Olson wrote:



[quote] 



 Nope, I'm still very happy.  As far as access to the sender goes,  

 I've never had reason to touch it since it was first wired in.  It  

 works plenty well for me and I can usually plan on the reading being  

 dead on when I refuel.

 Tim



 On Aug 16, 2009, at 11:44 AM, "Pascal" <rv10builder(at)verizon.net>  

 wrote:



> 

>

> I agree there is a proven improvement with the forward location and  

> with Matt's ball (which btw would never fit for me in my limited  

> space) however I remind the group the flip side to this. A while  

> back Tim Olson and the Grumpy General, two people I respect,  

> mentioned that there is a  brief time the pump is actually even on,  

> take off and landing. The time it actually caused an issue was  

> rather brief and played a minor issue in the total scheme of things.

>> From a part of the e-mail by Tim, written last January- " While I  

>> do see the

> increase in fuel flow, just like you do, with mine installed in the  

> stock location, it doesn't cause me any headaches.  I only use the  

> fuel boost for maybe 60 seconds during takeoff, and even on landing  

> if I do, it's only for about 60 seconds again....just that  

> timeframe that I'm under about 500' AGL If you only use it a couple  

> minutes during the flight, it won't change those readings much at  

> all. I've consistently been accurate to within about .1-.2 gallons  

> over a 40-45 gallon flight, so it's just not worth worrying about.  

> In over 400 hours I've never had a fuel fill up that had any  

> noticeable amount of difference over what the totalizer  told me I  

> should be adding."

> By all means consider moving the location to the front, especially  

> if you haven't done the install already per the plans, but for  

> those who already have the sensor in place, think about this before  

> you make a modification from the Van's plans- new hoses?, new  

> setups?.. ask yourself with this information if it's worth the  

> effort?

> Just bringing a difference perspective for anyone who worried about  

> this, as I did initially.

>

> Tim may have changed his mind on this, if so Tim please advise.

>

> Pascal

> #40720

> --------------------------------------------------

> From: "John Cox" <johnwcox(at)pacificnw.com>

> Sent: Sunday, August 16, 2009 9:45 AM

> To: <rv10-list(at)matronics.com>

> Subject: RE: Fuel Flow variations

>

>> 

>>

>> Matt Dralle offered a small but well built fluid accumulator which  

>> can

>> assist the dampening pressure fluctuations of pump actions.  If the

>> accumulator is used and placed prior to the sensor the degree of

>> fluctuation should be reduced at the point of indication.

>>

>>

>> John

>> #40600

>>

>> --

jump2(at)sbcglobal.net
Guest

Posted: Sun Aug 16, 2009 5:15 pm Post subject: Fuel Flow variations

Has any one read their manuals from EI or JPI and How they are to mount their Transducer? You can learn a lot from manuals. Or go look at a shop and see how the Certified group put theirs in.,

 Has anyone thought maybe your sucking air in your line just enough? Not big enough to see fuel stain  but still sucking air. How about your bypass is opening and closing.Anything passing through you mechanical pump. Just a little leak passing by?

Everyone in Texas know how their fuel acst when its 100degree plus and just think when you stop and have that 100 dollar hamburger and then go and get in it to crank up.

 These are just some of my thougths not knowing everyones paticular case but it is food for thought.

Keep asking, but try reading, sometime you learn more then you need.

Ok I'm not here to answere .

Patrick Thyssen

Yes I'm  flying sorta When the electrons let me.

 



--- On Sat, 8/15/09, William Curtis <wcurtis(at)nerv10.com> wrote:

 	  Quote: 	
		  

From: William Curtis <wcurtis(at)nerv10.com>

Subject: Re: Fuel Flow variations

To: rv10-list(at)matronics.com

Date: Saturday, August 15, 2009, 4:24 PM



Yes, this is the consensus of AFS, EI, Airflow et al.  For this reason as well as easier access to the transducer, I have moved my fuel flow transducer from the tunnel to the servo output port.  With some additional parts from AN Plumbing, I was able to put it there without any change to the hoses.

   

 William

 http://wcurtis.nerv10.com/

 



 

 On Sat, Aug 15, 2009 at 4:24 PM, Deems Davis <[url=/mc/compose?to=deemsdavis(at)cox.net]deemsdavis(at)cox.net[/url]> wrote:

  	  Quote: 	
		  --> RV10-List message posted by: Deems Davis <[url=/mc/compose?to=deemsdavis(at)cox.net]deemsdavis(at)cox.net[/url]>

 

Is anyone experiencing variations in fuel flow readings?

I am experiencing variations in fuel flow readings of up to .5 gph.  Typically the variations are .1-.3 gph. I've got the flow meter mounted in the tunnel per Van's plans. And after talking to Don Rivera (at) Airflow Performance, he believes that the variations are due to the location of the meter. Apparently the optimum location is between the servo and the distribution spider. I've searched the archives, as I recalled some dialogue on this subject and basically verified what Don said about mounting location.

 I'm interested to know if others are experiencing similar readings and any attempts to improve or correct the situation.



Thanks



Deems Davis N519PJ

http://deemsrv10.com/

 br> www.matronics.com/Navigator?RV10-List" target="_blank">http://www.matronics.com/Navigator?RV10-List

 ronics.com/" target="_blank">http://forums.matronics.com

 Matt Dralle, List Admin.

 =====





http://www.matronics.com/Navigator?RV10-lank" href="http://forums.matronics.com">http://forums.matronics.com 	


	
 [quote][b]

dlm46007(at)cox.net
Guest

Posted: Sun Aug 16, 2009 5:34 pm Post subject: Fuel Flow variations

The GRT display with the EIS system has a lean function and by using it EGTs

are used rather than fuel flow. GRT users can invoke the lean function and

watch the individual cylinders peak and then go lean: first to peak is boxed

green? And last to peak is boxed white? If all the minus numbers for EGT

data are between 0 to -30 and the engine is smooth I then look at the fuel

flow. 



--

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Mon Aug 17, 2009 8:36 am Post subject: Fuel Flow variations

Thanks to all for their responses on this topic.



What's driving me on this, is that I want to balance my injectors so I 

can begin to play with LOP, and I'd like to have a more stable 

measurement when collecting the data for the injectors. Thanks to the 

link on Matt's bulb. I've got an email into him with some questions. Has 

anyone had any experience with this? I'm just wondering if this is one 

of those thing that should work i theory, but..... ? Also someone 

mentioned a lack of space to install. I've asked Matt for dimensions. If 

it works this might be the easiest 'fix'. We'll see,

Deems Davis N519PJ

http://deemsrv10.com/index.html



 	  Quote: 	
		   *

 *

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Aug 17, 2009 8:55 am Post subject: Fuel Flow variations

I may be wrong here, but I don't think you get any valuable info from 

fuel flow when trying to match injectors.  The data point is EGT ...... 

which you work towards balancing the readings.

What info do you get from fuel flow in this scenario?

Linn

do not archive

Deems Davis wrote:

 	  Quote: 	

 Thanks to all for their responses on this topic.

 What's driving me on this, is that I want to balance my injectors so I 

 can begin to play with LOP, and I'd like to have a more stable 

 measurement when collecting the data for the injectors. Thanks to the 

 link on Matt's bulb. I've got an email into him with some questions. Has 

 anyone had any experience with this? I'm just wondering if this is one 

 of those thing that should work i theory, but..... ? Also someone 

 mentioned a lack of space to install. I've asked Matt for dimensions. If 

 it works this might be the easiest 'fix'. We'll see,

 Deems Davis N519PJ

 http://deemsrv10.com/index.html

> *

> *

rene(at)felker.com
Guest

Posted: Mon Aug 17, 2009 9:12 am Post subject: Fuel Flow variations

You plot individual cylinder peak against fuel flow.  Trying to get them all

to peak within .2 gph or better.  Because of sensor placement errors and

sensor accuracy, the actual EGT does not matter, just at what fuel flow it

peaks.



Rene' Felker

RV-10 N423CF Flying

801-721-6080



--

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