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Fuel Transfer

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kj7sr(at)earthlink.net
Guest

Posted: Fri Jul 06, 2007 8:40 am Post subject: Fuel Transfer

I am having trouble getting fuel from my wing tanks to transfer to the main tank. I put  forward facing tubes from the fuel caps into the airstream but they don't seem to pressurize the tanks enough to permit transfer. I was thinking of putting siphon bulbs such as from boat remote tanks into the fuel lines in the cabin. I would appreciate any other ideas.

  

 Chuck Bloom

 Missoula, MT

 Kitfox Model 1 #8

 Rotax 503

  

  

 

  [quote][b]

clemwehner(at)sbcglobal.n
Guest

Posted: Fri Jul 06, 2007 9:28 am Post subject: Fuel Transfer

This comes up  every few years. About 6-8 years ago we had a discussion about increasing the  pressure in the tanks. I did an experiment of taking a fuel cap and putting a  little funnel on the end of the tube facing into the wind.   I hooked  my airspeed indicator to the tube, then used my leaf blower and blew air at it  at 80 MPH.  Then I took the funnel off and the airspeed went down. Funnel  on-more airspeed, funnel off-less airspeed.  The funnel seems to catch more  wind and increase the pressure in the fuel cap tube. Try it yourself.  I  used little plastic funnels that my doc gave me. They go on the little scope  that he looks into your ears with), but you could make a little funnel out of  anything, even cardboard to try the experiment.

  

  

  

 Clem Wehner  (the other Clem)  Hmmmm, what's the chances of 2 Clems on this  list?

 KFIV,912

 Lawton  OK

  

 [quote]   

   --

msm_9949(at)yahoo.com
Guest

Posted: Fri Jul 06, 2007 11:44 am Post subject: Fuel Transfer

Hi Charles.

   

  What happens when you try to blow through the fuel cap vents?



Charles Bloom <kj7sr(at)earthlink.net> wrote:

  [quote]      I am having trouble getting fuel from my wing tanks to transfer to the main tank. I put  forward facing tubes from the fuel caps into the airstream but they don't seem to pressurize the tanks enough to permit transfer. I was thinking of putting siphon bulbs such as from boat remote tanks into the fuel lines in the cabin. I would appreciate any other ideas.

   

  Chuck Bloom

  Missoula, MT

  Kitfox Model 1 #8

  Rotax 503

   

   

  

[quote][b]          Ready for the edge of your seat?  [url=http://us.rd.yahoo.com/evt=48220/*http://tv.yahoo.com/]Check out tonight's top picks[/url] on Yahoo! TV.    [quote][b]

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Fri Jul 06, 2007 12:20 pm Post subject: Re: Fuel Transfer

Chuck,

My fuel transfer is too slow to suit me also, and the wing tank flow stops easily, especially when the fuel is low.  The transfer flow varies from about 8 to 13 gallons per hour.



I have a right wing tank that transfers to the panel tank.  The fuel line is 1/4 in. ID urathane.  The line runs from the wing tank forward above the door and down the diagonal fuselage tube to the panel tank.  There is a shut off valve and an in line filter in the line.  The panel tank vent line runs to the top of the wing tank.



I think the in line filter is restricting the flow some but believe the biggest cause of the problem is not enough down slope in the line from the tank to where it starts down the diagonal tube. 



The kitfox fuel systems that I know of that worked well all ran the fuel line from the wing tank imediately down behind the seat, forward under the seat and door then back up to the panel tank.  I have not gone with that route because I don't like the idea of that significant low spot in the line that could collect water and maybe even freeze.



I keep looking for some 5/16 ID urathane fuel line to try but no luck so far.  There is plenty of 5/16 rubber fuel line on the market but I am using premix oil in the fuel and have heard that the oil will deterioriate the

rubber fueline.

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_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Fri Jul 06, 2007 12:40 pm Post subject: Fuel Transfer

By main  tank I assume you mean a panel tank.  It may need a vent, possibly rear  facing above the level of the wing tank to allow fuel to flow down into  it.

 Do you  have a vent on your main tank?

  

  

[img]cid:772442619(at)06072007-1285[/img]  

 Noel Loveys, RPP, AME intern

 Campbellton, Newfoundland, 

 Canada

 Kitfox Mod III-A, 582, B box, Ivo IFA

 Aerocet 1100s

 noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)

 

 

 Do not archive

 



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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

n981ms(at)yahoo.com
Guest

Posted: Fri Jul 06, 2007 12:48 pm Post subject: Fuel Transfer

I suspect something is wrong with your system.  Gravity should feed the main tank and I would hesitate to depend on anything else.  I would check every line into and out of every tank for obstruction.  I think you will find one some where.  Fluid will flow down hill if it has vacuum relief above.

   

  Maxwell

  S6 TD IO240



Marco Menezes <msm_9949(at)yahoo.com> wrote:

  [quote]  Hi Charles.

   

  What happens when you try to blow through the fuel cap vents?



Charles Bloom <kj7sr(at)earthlink.net> wrote:

  [quote]      I am having trouble getting fuel from my wing tanks to transfer       [url=http://us.rd.yahoo.com/evt=48250/*http://searchmarketing.yahoo.com/arp/sponsoredsearch_v9.php?o=US2226&cmp=Yahoo&ctv=AprNI&s=Y&s2=EM&b=50]Pinpoint customers [/url]who are looking for what you sell.    [quote][b]

john(at)leptron.com
Guest

Posted: Fri Jul 06, 2007 2:59 pm Post subject: Fuel Transfer

I put a "t" in the line at the low spot and installed a fuel drain at that

point"

John Oakley



"I have not gone with that route because I don't like the idea of that

significant low spot in the line that could collect water and maybe even

freeze."

pwmac(at)sisna.com
Guest

Posted: Fri Jul 06, 2007 6:42 pm Post subject: Fuel Transfer

Very true especially if you have a non standard header tank. The M4 

header has a low point over an inch below the outlet so a tee in the 

outlet line should present no problem.

Paul

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

At 04:58 PM 7/6/2007, you wrote:

 	  Quote: 	
		  



I put a "t" in the line at the low spot and installed a fuel drain at that

point"

John Oakley



"I have not gone with that route because I don't like the idea of that

significant low spot in the line that could collect water and maybe even

freeze."

pwmac(at)sisna.com
Guest

Posted: Fri Jul 06, 2007 6:42 pm Post subject: Fuel Transfer

You are correct that you have resistance to flow in your gravity 

lines. Technically 3/8" would be the proper size. I think the 

manufacturer is way marginal with the specified 5/16" lines. Anyway 

make sure you have no high points where a a vapor/air bubble can 

collect, and that the line gradually goes down hill.

Of course nobody uses rubber for fuel lines. Regular automotive fuel 

lines are pretty impervious to any hydrocarbons like 2-stroke oil. Go 

to the auto store and get SAE R-7 hose in as big as is practical for 

your application. If you have a filter between the tank and the 

header, please remove it, and same for the valve. Very bad practice 

to have pressure loss devices in a critical place as a gravity feed 

system. If you think you must have a valve go to a 3/8" size as it 

orifice should be adequate. The hardware store valves work 

fine,  just find the correct fitting to adapt to the chosen hose.

Last of all make sure your vend is free of any restrictions.



Regards, Paul

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

At 02:20 PM 7/6/2007, you wrote:

 	  Quote: 	
		  



Chuck,

My fuel transfer is too slow to suit me also, and the wing tank flow 

stops easily, especially when the fuel is low.  The transfer flow 

varies from about 8 to 13 gallons per hour.



I have a right wing tank that transfers to the panel tank.  The fuel 

line is 1/4 in. ID urathane.  The line runs from the wing tank 

forward above the door and down the diagonal fuselage tube to the 

panel tank.  There is a shut off valve and an in line filter in the 

line.  The panel tank vent line runs to the top of the wing tank.



I think the in line filter is restricting the flow some but believe 

the biggest cause of the problem is not enough down slope in the 

line from the tank to where it starts down the diagonal tube.



The kitfox fuel systems that I know of that worked well all ran the 

fuel line from the wing tank imediately down behind the seat, 

forward under the seat and door then back up to the panel tank.  I 

have not gone with that route because I don't like the idea of that 

significant low spot in the line that could collect water and maybe 

even freeze.



I keep looking for some 5/16 ID urathane fuel line to try but no 

luck so far.  There is plenty of 5/16 rubber fuel line on the market 

but I am using premix oil in the fuel and have heard that the oil 

will deterioriate the

rubber fueline.



--------

Tom Jones

Classic IV, Phase one

503 Rotax, 72 inch Two blade Warp

Ellensburg, WA





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7suds(at)Chartermi.net
Guest

Posted: Sat Jul 07, 2007 4:42 am Post subject: Fuel Transfer

Tom,

On my model 4 I ran 2 wing tanks and a 10 gal panel tank. The wing tanks 

were plumbed into the top of the panel tank with 1/4 tygon tubing that ran 

down the inside forward door post. Each wing tank had a shutoff and the 

panel tank was vented back to the right wing tank. After I filled the wing 

tanks I had a piece of tygon tubing I would put on the cap and gently blow 

until the line was flowing full and then shut off, then when I was flying 

and wanted to transfer I opened the wing valve and would get solid flow, if 

I ever lost flow in flight I was normally able to slip and get it folwing 

again. I did an experiment once and removed the vent line from the wing tank 

and put it up through the top right rear canopy, thus allowing the ram 

pressure from the wing tank cap to pressurize the tank and not the return 

vent, flow was great but I opted not to leave it that way in case I would 

start transfer and forget I could be pushing fuel out of the plane, I also 

pre mixed.

(do not archive)

Lloyd

Rebuild

Mod 5 912ul

UP Mi.



---

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Sat Jul 07, 2007 11:41 am Post subject: Fuel Transfer

At 09:38 AM 7/6/2007, you wrote:

 	  Quote: 	
		  I am having trouble getting fuel from my wing tanks to transfer to 

the main tank. I put  forward facing tubes from the fuel caps into 

the airstream but they don't seem to pressurize the tanks enough to 

permit transfer.


	


Unfortunately, the forward facing vents do not usually promote 

transfer as they pressurize the system end to end. They do increase 

the pressure at the outlet, which is good, and help if there is some 

kind of obstruction that generates a significant internal pressure drop.



 	  Quote: 	
		  I was thinking of putting siphon bulbs such as from boat remote 

tanks into the fuel lines in the cabin. I would appreciate any other ideas.


	


As offered by others, first go through and check your lines. Pull 

both ends and blow. Any significant resistance should be checked out. 

There have been fuel lines that swelled shut internally, with no 

evidence externally. If everything checks out, check your line sizes. 

I use 3/8" from the wing tanks to the header and on to the fuel 

valve. From there I go to 1/4" to the pump and on to the carbs. The 

exception is that my header vent is 1/4". Check your routing for 

losses. These will be in the form of excessive line length, too many 

elbows, too many junctions. You already heard about the filters. I 

wouldn't take such an extreme position, but I would recommend that 

any filter in the gravity side of the system have a negligible 

pressure drop. (I.e. use BIG filters. I use a huge race car filter 

just after my header tank.) I think the ideal fuel line is bent 

aluminum tube. You can use large sizes, the inside is smooth, bends 

are smooth, it lasts a long time, (assuming it's mounted correctly,) 

and it's light. It's also pretty easy to install.

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

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