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Fuel Flow Problems, Again! (Vixen, Series-5)
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FlyboyTR

Joined: 04 Nov 2006
Posts: 215
Location: Mobile, Alabama

Posted: Sat Oct 31, 2009 2:34 pm Post subject: Re: Fuel Flow Problems, Again! (Vixen, Series-5)

Lynn,

I am considering cutting the fitting as you suggested.  However, looking at it, I really don't believe there is a finger strainer there!  I guess I need to check the builders log and see if the rib should be cut down.  The fuel line is about 3/4" higher than the fitting.



Note...My system is NOT sucking air!  This last problem happened about 35 minutes flight time after both tanks were filled to the brim for a 400 mile flight.  I get air in my filters and they are AIR LOCKING...sort of like a vapor lock.  Don't know where the air comes from!  This problem doesn't happen very ofter...but when it does the fuel stops flowing.  Once I get the fuel to flow again, the air gets pushed out/down and all is well...until the next time it happens.



Thanks again for the plastic under the fitting trick!  

OH...are there finger strainers still available for purchase?



Travis

_________________
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
www.enotam.net (My Flying Info Website)

Fox5flyer
Guest

Posted: Sat Oct 31, 2009 3:58 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

Travis, that thing that looks like a brass bushing in your tank (the thing 

that your 90 degree fitting screws into) is probably your finger strainer.

Deke



---

FlyboyTR

Joined: 04 Nov 2006
Posts: 215
Location: Mobile, Alabama

Posted: Sat Oct 31, 2009 4:03 pm Post subject: Re: Fuel Flow Problems, Again! (Vixen, Series-5)

Deke,

If that's the case, then I will be unscrewing it from the tank itself...not another bushing?  Is that right?

_________________
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
www.enotam.net (My Flying Info Website)

Fox5flyer
Guest

Posted: Sat Oct 31, 2009 5:03 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

Correct.

D

do not archive



---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sat Oct 31, 2009 5:14 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

Can you stick a mirror into the tank and see the fitting area? Or is  

there a baffle in the way?

In the case of my tank(s), that outer brass IS the finger strainer,  

like Deke suggested.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 804.3 hrs

Countdown to 1000 hrs--196 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Oct 31, 2009, at 8:03 PM, FlyboyTR wrote:



 	  Quote: 	
		   



 Deke,

 If that's the case, then I will be unscrewing it from the tank  

 itself...not another bushing?  Is that right?



 --------

 Travis Rayner

 Mobile, AL

 Skystar Vixen, N-789DF

 Continental IO-240,  Prince P-Tip Prop

 ADI-II Autopilot

 AnyWhereMap Navigation with weather





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 70285#270285

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sat Oct 31, 2009 5:58 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

Sorry, I got the notion that *you* thought it was sucking air after I  

read this:



  " If by chance the system air-locks...at least now I can close the  

vent line and force the system to pull from the tanks, rather than  

sucking air."



I see a bubble of air in my filters too, and I've seen this in almost  

every glass filter fuel system that I've owned...which is  

several....and in others that I've observed over the years. It never  

seems to bother the fuel flow, it just seems to bother people who  

look at it. Maybe that's why people like the filters that they can't  

see into....you know....out of sight, out of mind. I've seen glass  

filters standing almost straight up, like yours and mine, and I've  

seen them laying on their side, like my third filter which lays  

almost horizontally inside my center console. Seeing this air doesn't  

bother me as gravity keeps the fuel flowing in my system, and fuel is  

heavier than air, and a bubble of air isn't strong enough to keep the  

fuel from falling downhill inside that filter.....IF there is  

sufficient venting above to ALLOW the fuel to fall. If my brand of  

physics is wrong, I'd like to know why I haven't had any fuel-flow- 

related problems in over 800 hours and billions of gallons of  

fuel....oh, wait, that's that guy in Canada that uses all that  

fuel....let's says roughly 3200 gallons of fuel passed through the  

system in that time.

Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 804.3 hrs

Countdown to 1000 hrs--196 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Oct 31, 2009, at 6:34 PM, FlyboyTR wrote:



 	  Quote: 	
		   



 Lynn,

 I am considering cutting the fitting as you suggested.  However,  

 looking at it, I really don't believe there is a finger strainer  

 there!  I guess I need to check the builders log and see if the rib  

 should be cut down.  The fuel line is about 3/4" higher than the  

 fitting.



 Note...My system is NOT sucking air!  This last problem happened  

 about 35 minutes flight time after both tanks were filled to the  

 brim for a 400 mile flight.  I get air in my filters and they are  

 AIR LOCKING...sort of like a vapor lock.  Don't know where the air  

 comes from!  This problem doesn't happen very ofter...but when it  

 does the fuel stops flowing.  Once I get the fuel to flow again,  

 the air gets pushed out/down and all is well...until the next time  

 it happens.



 Thanks again for the plastic under the fitting trick!

 OH...are there finger strainers still available for purchase?



 Travis  



 --------

 Travis Rayner

 Mobile, AL

 Skystar Vixen, N-789DF

 Continental IO-240,  Prince P-Tip Prop

 ADI-II Autopilot

 AnyWhereMap Navigation with weather





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 70276#270276

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

lcfitt(at)sbcglobal.net
Guest

Posted: Sat Oct 31, 2009 7:10 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

The more centric feed location was intended to reduce the tendency to unport 

in long descents.  The T is to direct the fuel line aft to position the fuel 

line for wing folding.



There was discussion on the list about this issue when this mod came down. 

Some put inspection plates under the fitting.  I can agree that the mod 

helped in one area and hurt in another.  I guess the unintended consequences 

thing.



:Lowell

---

FlyboyTR

Joined: 04 Nov 2006
Posts: 215
Location: Mobile, Alabama

Posted: Sat Oct 31, 2009 7:58 pm Post subject: Re: Fuel Flow Problems, Again! (Vixen, Series-5)

Lynn,

This problem happens, usually, when my tanks are more than 1/2 - 3/4 full.  To my knowledge I've never "unported" the tank by descending at such an angle that the fuel moves away from the outlet.



As so often happens on this forum, someone will reply to a post by starting a new post with the same title (as happened to this thread).  If you haven't read my original post, please take a look.   I tried to explain the details and history of this problem that comes and goes...I would prefer for it to go!   



Once I'm back in the air...should this happen again, I will remove the filter element but keep the glass filter housing in place for observation.



Travis

_________________
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
www.enotam.net (My Flying Info Website)

FlyboyTR

Joined: 04 Nov 2006
Posts: 215
Location: Mobile, Alabama

Posted: Sat Oct 31, 2009 8:06 pm Post subject: Re: Fuel Flow Problems, Again! (Vixen, Series-5)

Sorry...I missed that... No, I have baffles in the tank. Can't see that area of the tank. ...which I could!

_________________
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
www.enotam.net (My Flying Info Website)

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 01, 2009 3:36 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

I've read all your posts, and all of any mail that comes into my  

email box....I don't go to the "site". The only thing problem that  

this creates is when somebody doesn't include a snippet of what they  

are replying to...like you did here. But this thread is current  

enough that even my poor memory allows me to "connect the dots." The  

other problem is when someone only gets the "digest" and includes 44  

messages in their reply, like I bitched about last week. : )



I doubt that the filter element is your problem. I'm keeping all of  

my filters, no matter how much certain engineers might (for me)  

confuse the issue with talk of surface tension, etc., my system flows  

fuel as long as there's fuel in the system to flow...nudge, nudge,  

wink, wink. ; )

Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 804.3 hrs

Countdown to 1000 hrs--196 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Oct 31, 2009, at 11:58 PM, FlyboyTR wrote:



 	  Quote: 	
		   



 Lynn,

 This problem happens, usually, when my tanks are more than 1/2 -  

 3/4 full.  To my knowledge I've never "unported" the tank by  

 descending at such an angle that the fuel moves away from the outlet.



 As so often happens on this forum, someone will reply to a post by  

 starting a new post with the same title (as happened to this  

 thread).  If you haven't read my original post, please take a  

 look.   I tried to explain the details and history of this  

 problem that comes and goes...I would prefer for it to go!  [Laughing]



 Once I'm back in the air...should this happen again, I will remove  

 the filter element but keep the glass filter housing in place for  

 observation.



 Travis  



 --------

 Travis Rayner

 Mobile, AL

 Skystar Vixen, N-789DF

 Continental IO-240,  Prince P-Tip Prop

 ADI-II Autopilot

 AnyWhereMap Navigation with weather





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 70317#270317

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

FlyboyTR

Joined: 04 Nov 2006
Posts: 215
Location: Mobile, Alabama

Posted: Sun Nov 01, 2009 5:43 am Post subject: Re: Fuel Flow Problems, Again! (Vixen, Series-5)

Lynn,

...you get to read a lot of email!  



I really don't want to get rid of my filters either.  We are still only talking about one filter between a wing tank and the header tank.  Once the fuel is in the header tank it should then benefit from the "suction" of the mechanical pump.



My last two hurdles are removing the wing tank outlet fitting to check the finger strainers and cutting the root rib on the wing so the fuel line doesn't have to have a hump in it before descending down towards the header tank.  Thanks again for all your input...always appreciated!



Travis  



 	  Lynn Matteson wrote: 	
		  I've read all your posts, and all of any mail that comes into my  email box....I don't go to the "site". 



I doubt that the filter element is your problem. I'm keeping all of  

my filters, no matter how much certain engineers might (for me)  

confuse the issue with talk of surface tension, etc., my system flows  

fuel as long as there's fuel in the system to flow...nudge, nudge,  

wink, wink. ; )

Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 804.3 hrs

Countdown to 1000 hrs--196 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Oct 31, 2009, at 11:58 PM, FlyboyTR wrote:



 	  Quote:

_________________
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
www.enotam.net (My Flying Info Website)

thesupe(at)hotmail.com
Guest

Posted: Sun Nov 01, 2009 7:12 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

When I first got my Avid MK IV C I put filters on both sides between the wing tanks and the header tank.  All was fine for a while (about 10-15 hrs) till one evening I took off from my strip and as I climbed out and got to 450' C the engine started to miss and spit.  I ended up landing in a neighbors field with no dammage to me or the plane.  What had happened I found out the next day C was the filter on the tank I was using started to plug just a bit and so the flow was reduced.  The engine never did die C but would not run up above about 4000 rpm.  Durring the takeoff C it was turning up about 6200 C and when the small header tank was emptied C things got "interesting".  I posted this account on the Avid list C and Steve Winder C who ran the Avid factory for years said NEVER HAVE FILTERS BETWEEN THE WING TANKS AND THE HEADER TANK.  He used all capitol letters also!  He said that it takes very little to stop or slow the gravity flow C and ofcourse that is what caused my problem.  He also said C that the header tank works as a gascolator to filter the fuel so the filters between the tanks aren't needed.  I had a final filter between the header tank and the fuel pump C and so to gaurd against that one plugging and putting me in the trees C I put in a T in my fuel line and added a second filter alongside the first one and then a T back into the fuel line with a small valve to stop the flow through that filter.  When I'm taking off C I open that valve and then close it after I get up to 750' or so.  If the main filter ever starts to plug while in flight C I will open the valve for the second filter and the fuel will  be able to flow through that one and I will stay out of the trees.  So far that has worked good for me and I still have potentialy three filters to stop any crud getting to the carb.  The header tank C the inline filter C pluss the backup filter which will only be used if the first inline filter plugs.  To each his own C but this works for me.  I have always used the Fram paper filters and they have worked good for me.

 Take care C  Jim Chuk

[quote] Subject: Re: Fuel Flow Problems C Again! (Vixen C Series-5)

 From: flyboytr(at)bellsouth.net

 Date: Sun C 1 Nov 2009 05:43:45 -0800

 To: kitfox-list(at)matronics.com

 --> Kitfox-List message posted by: "FlyboyTR" <flyboytr(at)bellsouth.net>

 Lynn C

 ...you get to read a lot of email! [Shocked] 

 I really don't want to get rid of my filters either. We are still only talking about one filter between a wing tank and the header tank. Once the fuel is in the header tank it should then benefit from the "suction" of the mechanical pump.

 My last two hurdles are removing the wing tank outlet fitting to check the finger strainers and cutting the root rib on the wing so the fuel line doesn't have to have a hump in it before descending down towards the header tank. Thanks again for all your input...always appreciated!

 Travis 

 Lynn Matteson wrote:

 > I've read all your posts C and all of any mail that comes into my email box....I don't go to the "site". 

 > 

 > I doubt that the filter element is your problem. I'm keeping all of 

 > my filters C no matter how much certain engineers might (for me) 

 > confuse the issue with talk of surface tension C etc. C my system flows 

 > fuel as long as there's fuel in the system to flow...nudge C nudge C 

 > wink C wink. ; )

 > 

 > 

 > Lynn Matteson

 > Kitfox IV Speedster C taildragger

 > Jabiru 2200 C #2062 C 804.3 hrs

 > Countdown to 1000 hrs--196 to go

 > Sensenich 62"x46" Wood prop

 > Electroair direct-fire ignition system

 > Rotec TBI-40 injection

 > Status: flying (and learning)

 > 

 > 

 > 

 > 

 > 

 > 

 > On Oct 31 C 2009 C at 11:58 PM C FlyboyTR wrote:

 > 

 > 

 > > 

 > > 

 > > 

 > > 

 > 

 --------

 Travis Rayner

 Mobile C AL

 Skystar Vixen C N-789DF

 Continental IO-240 C Prince P-Tip Prop

 ADI-II Autopilot

 AnyWhereMap Navigation with weather

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=270420#270420

 > 

 		 	   		  New Windows 7: Find the right PC for you. Learn more.   	  Quote: 	
		  [b]

Fox5flyer
Guest

Posted: Sun Nov 01, 2009 8:01 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

I know this thread has been going on forever and those who have wing tank 

filters will probably keep them.   Fuel flow is probably one of the most 

important parts of our airplane so talking this to death can't hurt a thing. 

Here's my take, for whatever it's worth.

Ideally, "IMO" the lines from the wing tanks to the header should be as 

large as practicable...3/8 ID would be good.  To keep the head pressure as 

high as possible there should be no (unnecessary) restrictions between the 

tanks and the header, meaning no filters, valves, unnecessary fittings, or 

reducing fittings that restrict flow.  After the header, the same applies, 

however, it's obvious that one needs at minimum a shutoff valve and usually 

a fuel pump of some sort.  Since most fuel pumps are meant to push fuel, not 

suck, it should be at the lowest point in the system, generally just after 

the header and as close to it as practical.  After the fuel pump things are 

not so critical as most pumps can push fuel pressure and volume far beyond 

what static flow can provide.  Obviously, the 582s with diaphragm pumps 

wouldn't be very practical to be placed at this point, but to continue. 

There should be a shut off valve, generally on the console or wherever it's 

located that is easy to reach, again, IMO, the next restriction should be 

the filter.  This should be a high flow filter and could be located on the 

firewall and be the last line of defense before it goes to the carb/TB/etc. 

Again, I stated "ideally" and is only my opinion.  There are many other 

methods that work and some that don't, but as I recall a study was done at 

some point about forced landings and most were caused by fuel starvation. 

Everything that is put into the system between the fuel tanks and the engine 

is a restriction of some sort.  Add them all up and it can be significant 

and even though the system may be working it may be marginally close to 

failure without one knowing it.

Personally, I don't feel the filters in the lines from the tanks to the 

header are necessary at all.  Between the finger strainers and the natural 

settling action of the header, plus the fuel sump at the bottom of the 

header, there is more than enough there to clean up the big stuff.  The 

final filter at the firewall will take care of anything that somehow reaches 

that point.

I expect that some will take issue with this, and that is fine and I'd like 

to hear it.  Just be nice.  

Have a great day!

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 438+ TT

"If you put the federal government in charge of the Sahara

Desert, in five years there'd be a shortage of sand."

-- Nobel prize-winning economist Milton Friedman (1912-2006)



---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 01, 2009 8:46 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

The only problem I have....and this is just a shade-tree mechanics  

view...is the paper filter. It is said that they will clog if water  

gets to them. I can see the benefit of not having a filter in the  

line to the header tank, as the header tank DOES work like a  

gascolator, and as such will catch (and allow for the sampling of)  

any crud that might get there. I put the filters in my down...to the  

header...lines because I wanted to see any crud that just got into  

those lines from airport A, or airport B, etc., or from my own 300- 

gallon tank at home.

Like you said, to each his own, and future or current builders will  

be able to choose for themselves what they think is right. And of  

course, each DAR will have his/her own views on what they will allow.

Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 805.4 hrs

Countdown to 1000 hrs--195 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Nov 1, 2009, at 10:06 AM, Jim_and_Lucy Chuk wrote:

 	  Quote: 	
		   When I first got my Avid MK IV, I put filters on both sides between  

 the wing tanks and the header tank.  All was fine for a while  

 (about 10-15 hrs) till one evening I took off from my strip and as  

 I climbed out and got to 450', the engine started to miss and  

 spit.  I ended up landing in a neighbors field with no dammage to  

 me or the plane.  What had happened I found out the next day, was  

 the filter on the tank I was using started to plug just a bit and  

 so the flow was reduced.  The engine never did die, but would not  

 run up above about 4000 rpm.  Durring the takeoff, it was turning  

 up about 6200, and when the small header tank was emptied, things  

 got "interesting".  I posted this account on the Avid list, and  

 Steve Winder, who ran the Avid factory for years said NEVER HAVE  

 FILTERS BETWEEN THE WING TANKS AND THE HEADER TANK.  He used all  

 capitol letters also!  He said that it takes very little to stop or  

 slow the gravity flow, and ofcourse that is what caused my  

 problem.  He also said, that the header tank works as a gascolator  

 to filter the fuel so the filters between the tanks aren't needed.   

 I had a final filter between the header tank and the fuel pump, and  

 so to gaurd against that one plugging and putting me in the trees,  

 I put in a T in my fuel line and added a second filter alongside  

 the first one and then a T back into the fuel line with a small  

 valve to stop the flow through that filter.  When I'm taking off, I  

 open that valve and then close it after I get up to 750' or so.  If  

 the main filter ever starts to plug while in flight, I will open  

 the valve for the second filter and the fuel will  be able to flow  

 through that one and I will stay out of the trees.  So far that has  

 worked good for me and I still have potentialy three filters to  

 stop any crud getting to the carb.  The header tank, the inline  

 filter, pluss the backup filter which will only be used if the  

 first inline filter plugs.  To each his own, but this works for  

 me.  I have always used the Fram paper filters and they have worked  

 good for me.

 Take care,  Jim Chuk

 > Subject: Re: Fuel Flow Problems, Again! (Vixen,  

 Series-5)

 > From: flyboytr(at)bellsouth.net

 > Date: Sun, 1 Nov 2009 05:43:45 -0800

 > To: kitfox-list(at)matronics.com

 >

 > 

 <flyboytr(at)bellsouth.net>

 >

 > Lynn,

 > ...you get to read a lot of email! [Shocked]

 >

 > I really don't want to get rid of my filters either. We are still  

 only talking about one filter between a wing tank and the header  

 tank. Once the fuel is in the header tank it should then benefit  

 from the "suction" of the mechanical pump.

 >

 > My last two hurdles are removing the wing tank outlet fitting to  

 check the finger strainers and cutting the root rib on the wing so  

 the fuel line doesn't have to have a hump in it before descending  

 down towards the header tank. Thanks again for all your  

 input...always appreciated!

 >

 > Travis

 >

 >

 > Lynn Matteson wrote:

 > > I've read all your posts, and all of any mail that comes into  

 my email box....I don't go to the "site".

 > >

 > > I doubt that the filter element is your problem. I'm keeping  

 all of

 > > my filters, no matter how much certain engineers might (for me)

 > > confuse the issue with talk of surface tension, etc., my system  

 flows

 > > fuel as long as there's fuel in the system to flow...nudge, nudge,

 > > wink, wink. ; )

 > >

 > >

 > > Lynn Matteson

 > > Kitfox IV Speedster, taildragger

 > > Jabiru 2200, #2062, 804.3 hrs

 > > Countdown to 1000 hrs--196 to go

 > > Sensenich 62"x46" Wood prop

 > > Electroair direct-fire ignition system

 > > Rotec TBI-40 injection

 > > Status: flying (and learning)

 > >

 > >

 > >

 > >

 > >

 > >

 > > On Oct 31, 2009, at 11:58 PM, FlyboyTR wrote:

 > >

 > >

 > > >

 > > >

 > > >

 > > >

 > >

 > 

 >

 > --------

 > Travis Rayner

 > Mobile, AL

 > Skystar Vixen, N-789DF

 > Continental IO-240, Prince P-Tip Prop

 > ADI-II Autopilot

 > AnyWhereMap Navigation with weather

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p 70420#270420

 >

 >

 >

 >

 >

 >

 > >

 >

 >

 New Windows 7: Find the right PC for you. Learn more._- 

 ============================================================ _- 

 ============================================================ _- 

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

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 01, 2009 9:17 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

Probably more important than where a person decides to place the  

filters, valves, etc., is the decision to do a flow test after all  

the plumbing is done. That might reveal more than all the theory in  

the world. If the flow test shows marginal flow, change something! If  

it doesn't......



One of the discoveries that I made while changing to the TBI in place  

of the Bing carb, was I hadn't realized how far up the "flow chart"  

the carb/TBI was located. With my gravity flow ONLY system, if I have  

to point the nose up very steeply with low fuel....like when the  

header tank supply is the only fuel available....that fuel will not  

make it up to the TBI/carb. You folks with high-mounted carbs are  

almost certain candidates for a pumped system.



If in doubt about the flow of your particular system, lay some  

masking paper on the side of the aircraft, and measure and plot where  

the various parts of the fuel system lie, and where the lines run.  

Draw these components onto the paper, then imagine the plane  

climbing, diving, banking, etc., and see where the fuel goes and also  

imagine a lower than normal fuel supply, and see where that leads you.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 805.4 hrs

Countdown to 1000 hrs--195 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Nov 1, 2009, at 10:28 AM, fox5flyer wrote:



[quote] 

 <fox5flyer(at)idealwifi.net>



 I know this thread has been going on forever and those who have  

 wing tank filters will probably keep them.   Fuel flow is probably  

 one of the most important parts of our airplane so talking this to  

 death can't hurt a thing. Here's my take, for whatever it's worth.

 Ideally, "IMO" the lines from the wing tanks to the header should  

 be as large as practicable...3/8 ID would be good.  To keep the  

 head pressure as high as possible there should be no (unnecessary)  

 restrictions between the tanks and the header, meaning no filters,  

 valves, unnecessary fittings, or reducing fittings that restrict  

 flow.  After the header, the same applies, however, it's obvious  

 that one needs at minimum a shutoff valve and usually a fuel pump  

 of some sort.  Since most fuel pumps are meant to push fuel, not  

 suck, it should be at the lowest point in the system, generally  

 just after the header and as close to it as practical.  After the  

 fuel pump things are not so critical as most pumps can push fuel  

 pressure and volume far beyond what static flow can provide.   

 Obviously, the 582s with diaphragm pumps wouldn't be very practical  

 to be placed at this point, but to continue. There should be a shut  

 off valve, generally on the console or wherever it's located that  

 is easy to reach, again, IMO, the next restriction should be the  

 filter.  This should be a high flow filter and could be located on  

 the firewall and be the last line of defense before it goes to the  

 carb/TB/etc. Again, I stated "ideally" and is only my opinion.   

 There are many other methods that work and some that don't, but as  

 I recall a study was done at some point about forced landings and  

 most were caused by fuel starvation. Everything that is put into  

 the system between the fuel tanks and the engine is a restriction  

 of some sort.  Add them all up and it can be significant and even  

 though the system may be working it may be marginally close to  

 failure without one knowing it.

 Personally, I don't feel the filters in the lines from the tanks to  

 the header are necessary at all.  Between the finger strainers and  

 the natural settling action of the header, plus the fuel sump at  

 the bottom of the header, there is more than enough there to clean  

 up the big stuff.  The final filter at the firewall will take care  

 of anything that somehow reaches that point.

 I expect that some will take issue with this, and that is fine and  

 I'd like to hear it.  Just be nice.  

 Have a great day!

 Deke Morisse

 Mikado Michigan

 S5/Subaru/CAP 438+ TT

 "If you put the federal government in charge of the Sahara

 Desert, in five years there'd be a shortage of sand."

 -- Nobel prize-winning economist Milton Friedman (1912-2006)



 ---

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

jareds(at)verizon.net
Guest

Posted: Sun Nov 01, 2009 12:35 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

I have not read most of the posts and you may have already gotten this info

but I will never get rid of my glass filters at the wing tanks.. VITAL in

flight to physically see the fuel flow and see whats maybe sitting in my

tanks.  What I don't see unless I look very close is the little bits of

fiberglass but I keep filter elements handy and change very often.  

As to the fuel flow..  Don Smythe cured my issues years ago when I was in

DC.  He said "Always down hill" and even with a little bump in the hoses its

ok but the critical one is the vent line.  And to me that's the biggest

obstical because its always in the way to making a neat cockpit but when I

am cruising along and my header tank fuel low light comes on I can always

look at my vent line and know its got a dip in it!

Hope that helps.

Jared

Nov 1, 2009 07:54:21 AM, kitfox-list(at)matronics.com wrote:

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

Lynn,

..you get to read a lot of email! [Shocked] 

I really don't want to get rid of my filters either.  We are still only talking about one filter between a wing tank and the header tank.  Once the fuel is in the header tank it should then benefit from the "suction" of the mechanical pump.

My last two hurdles are removing the wing tank outlet fitting to check the finger strainers and cutting the root rib on the wing so the fuel line doesn't have to have a hump in it before descending down towards the header tank.  Thanks again for all your input...always appreciated!

Travis  

Lynn Matteson wrote:

 	  Quote: 	
		   I've read all your posts, and all of any mail that comes into my  email box....I don't go to the "site". 

 I doubt that the filter element is your problem. I'm keeping all of  

 my filters, no matter how much certain engineers might (for me)  

 confuse the issue with talk of surface tension, etc., my system flows  

 fuel as long as there's fuel in the system to flow...nudge, nudge,  

 wink, wink. ; )

 Lynn Matteson

 Kitfox IV Speedster, taildragger

 Jabiru 2200, #2062, 804.3 hrs

 Countdown to 1000 hrs--196 to go

 Sensenich 62"x46" Wood prop

 Electroair direct-fire ignition system

 Rotec TBI-40 injection

 Status: flying (and learning)

 On Oct 31, 2009, at 11:58 PM, FlyboyTR wrote:

 >  

 > 

 > 

 > 

--------

Travis Rayner

Mobile, AL

Skystar Vixen, N-789DF

Continental IO-240,  Prince P-Tip Prop

ADI-II Autopilot

AnyWhereMap Navigation with weather

Read this topic online here:

http://forums.matronics.com/viewtopic.php?p 70420#270420

dwight purdy

Joined: 10 Feb 2006
Posts: 85

Posted: Sun Nov 01, 2009 1:58 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

I do not comment often but listen a lot.

  On this subject of fuel filters will say that in my 32 years of flying I 

have never seen a filter on a GA certified aircraft. That does not include 

any of the newer fuel injected ones. I have had a paper filter for a short 

time on my model II. While running premix and some ethanol in the fuel I was 

forced to land off field. Once that paper gets oil soaked water will not 

pass properly. Took the filter out and no problem.



Dwight Purdy

Model II

---

_________________
dwight
model II

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 01, 2009 3:58 pm Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

I think you'll find that the filter on a GA aircraft is disguised and  

called a gascolator...but I could be wrong.



Inside my Rotec TBI is what is called a "last chance" filter. It  

catches the bad stuff that would otherwise try to plug the 50-some  

holes in the fuel discharge tube. These holes are reportedly . 

010" (ten-thousandths of an inch) in diameter. I trust my Purolator  

glass filters to keep the last chance filter, and thence the fuel  

discharge tube, clean. I won't take my "pre-filters" out unless  

something or someone proves that this is an incorrect design. And as  

long as my gravity system flows more than twice what is needed by the  

engine, that likelihood seems remote.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 805.4 hrs

Countdown to 1000 hrs--195 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Nov 1, 2009, at 4:24 PM, Dwight Purdy wrote:



[quote] 



 I do not comment often but listen a lot.

  On this subject of fuel filters will say that in my 32 years of  

 flying I have never seen a filter on a GA certified aircraft. That  

 does not include any of the newer fuel injected ones. I have had a  

 paper filter for a short time on my model II. While running premix  

 and some ethanol in the fuel I was forced to land off field. Once  

 that paper gets oil soaked water will not pass properly. Took the  

 filter out and no problem.



 Dwight Purdy

 Model II

 ---

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

KeysFox

Joined: 05 Jan 2009
Posts: 137

Posted: Mon Nov 02, 2009 4:47 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

This extended discussion on fuel flow issues has been just the sort of

thing I want out of the list sereve.



When I unport my right wing tank during a prolonged descent with low fuel

(model IV with large tanks) I watch fuel drain down out of the vent line

until the glass tube inline filter housing empties and does not refill

unless I crack the seal on it on the ground, then fuel instantly flows.



This has occurred several times  even with new filter elements, clean

finger strainers in the tanks, new fuel lines throughout, and lots of

attention to straight fuel lines between wing tanks and header tank.



Rather than removing the in line filter elements, I may try placing some

larger openings in the elements. The idea being less resistance but

ability to monitor for crud.



Thanks to those who have posted comments and to the list serve manager for

making this (and other discussions possible.)



B J

N154K model IV



 	  Quote: 	
		   



 Sorry...I missed that...  No, I have baffles in the tank.  Can't see that

 area of the tank.  ...which I could! 



 --------

 Travis Rayner

 Mobile, AL

 Skystar Vixen, N-789DF

 Continental IO-240,  Prince P-Tip Prop

 ADI-II Autopilot

 AnyWhereMap Navigation with weather





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 70320#270320

_________________
B Jones
N154K
443-480-1023

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Mon Nov 02, 2009 6:12 am Post subject: Fuel Flow Problems, Again! (Vixen, Series-5)

Could it be that your vent line has a uphill/downhill portion in it?  

That could be one reason that the fuel won't fill the filters. What I  

*think* is happening is this:   You run the header tank low by using  

fuel from it instead of the tanks when you unport the wing tanks in  

your descent. Then with the plane at ground attitude, fuel tries to  

come down the fuel lines through the filters and into the header  

tank. Some does (maybe), but apparently not all unless you "crack the  

seal". I believe that when the fuel tries to flow into the header  

tank it is trying to overcome air trapped inside the header  

tank....trapped because of fuel that is trapped in the uphill/ 

downhill vent line, and can't be pushed uphill by the downflowing  

fuel in the fuel lines. I've had the same thing happen with my  

plane.....watching the vent line empty during the descent (and of  

course the fuel line is emptying at the same time....and I've been  

lucky enough to tip the plane to an attitude that allows for a "mid- 

air re-fueling" if you will. But I was very careful to make certain  

of there being NO uphill/downhill sections in my vent line.



It would seem to me that this scenario that I just suggested would  

require just a certain amount of fuel trying to come down the fuel  

lines *versus* a certain amount of fuel trapped in the  uphill/ 

downhill vent line, or a certain amount of volume of lines for this  

to happen.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 805.4 hrs

Countdown to 1000 hrs--195 to go

Sensenich 62"x46" Wood prop

Electroair direct-fire ignition system

Rotec TBI-40 injection

Status: flying (and learning)

On Nov 2, 2009, at 7:38 AM, bjones(at)dmv.com wrote:



 	  Quote: 	
		   



 This extended discussion on fuel flow issues has been just the sort of

 thing I want out of the list sereve.



 When I unport my right wing tank during a prolonged descent with  

 low fuel

 (model IV with large tanks) I watch fuel drain down out of the vent  

 line

 until the glass tube inline filter housing empties and does not refill

 unless I crack the seal on it on the ground, then fuel instantly  

 flows.



 This has occurred several times  even with new filter elements, clean

 finger strainers in the tanks, new fuel lines throughout, and lots of

 attention to straight fuel lines between wing tanks and header tank.



 Rather than removing the in line filter elements, I may try placing  

 some

 larger openings in the elements. The idea being less resistance but

 ability to monitor for crud.



 Thanks to those who have posted comments and to the list serve  

 manager for

 making this (and other discussions possible.)



 B J

 N154K model IV



> 

> <flyboytr(at)bellsouth.net>

>

> Sorry...I missed that...  No, I have baffles in the tank.  Can't  

> see that

> area of the tank.  ...which I could! 

>

> --------

> Travis Rayner

> Mobile, AL

> Skystar Vixen, N-789DF

> Continental IO-240,  Prince P-Tip Prop

> ADI-II Autopilot

> AnyWhereMap Navigation with weather

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p 70320#270320

>

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

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