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Low spot in fuel system

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Tom Jones

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

Posted: Sun Nov 26, 2006 1:26 pm Post subject: Low spot in fuel system

I have a nose tank (panel tank) in a Classic 4.  There is no header tank behind the seat.  The fuel system is built by the book.  Fuel line runs from the outlet at the foreward bottom center of the tank back to the on/off valve at the bottom of the panel, then foreward through the firewall.  The gascolator is on the lower right of the firewall.



There is a low spot in the fuel line at the on/off valve with the tail on the ground and a low spot in the line at the tank outlet when the plane is level.  I worry about water collecting in the low spots.  Has anyone figured out a way to eliminate these low spots in a fuel system like this?  Picture attached.



Tom Jones

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pwmac(at)sisna.com
Guest

Posted: Sun Nov 26, 2006 4:30 pm Post subject: Low spot in fuel system

Hi Tom,

Looks like you have a early IV-1200 instead of the Classic as the 

Classic and late 1200s had the behind the seat tank.

  Anyway I would advise you to reroute the fuel line so that is 

gradually slopes to the gascolator and does not have a low spot. 

Humps in the fuel line are problematic for causing flow stoppage due 

to bubbles  in the line. The new routing will probably require new 

tubing from the valve to the gacolator. Place the plane in a 

horizontal position the use a level to see how to route the new line 

to make sure it slopes down hill from the valve.

Regards, Paul

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



At 01:26 PM 11/26/2006, you wrote:

 	  Quote: 	
		  



I have a nose tank (panel tank) in a Classic 4.  There is no header 

tank behind the seat.  The fuel system is built by the book.  Fuel 

line runs from the outlet at the foreward bottom center of the tank 

back to the on/off valve at the bottom of the panel, then foreward 

through the firewall.  The gascolator is on the lower right of the firewall.



There is a low spot in the fuel line at the on/off valve with the 

tail on the ground and a low spot in the line at the tank outlet 

when the plane is level.  I worry about water collecting in the low 

spots.  Has anyone figured out a way to eliminate these low spots in 

a fuel system like this?  Picture attached.



Tom Jones





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=77104#77104





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Tom Jones

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

Posted: Sun Nov 26, 2006 5:17 pm Post subject: Re: Low spot in fuel system

Thanks Paul.  Yes I agree the line needs to slope down hill all the way to the gascolator.  I can't seem to figure out how to do that with the parts I have.  It is a Classic 4 but I think Skystar cleaned out all the miselaneous parts they had laying around left over from the XL model when they filled the crate it came in.

Tom Jones

dosmythe(at)cox.net
Guest

Posted: Sun Nov 26, 2006 5:28 pm Post subject: Low spot in fuel system

Tom,

    I have the Classic IV and my kit (Late 95) didn't come with a Gascalator 

or include it in the installation manual.  My low point is the header 

(located low behind passenger seat).  Just wondering why you have a 

gascalator?

Don Smythe

---

Tom Jones

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

Posted: Sun Nov 26, 2006 7:31 pm Post subject: Re: Low spot in fuel system

Don,

My Classic 4 did not come with a header tank for behind the seat.  I wish it would have, then I would not need the gascolator.  I purchased the gascolator as an option to install in the low point of the nose tank fuel system.



For what its worth, the wing tanks feed the nose tank instead of a header tank.  It looks like I may have purchased my kit just before you did.  I should have waited then maybe I would have received the good header tank system.



The problem I have run into is there is no way to plumb the fuel lines into the shutoff valve where it is designed to go and still have a continuous down hill flow.



Tom Jones

dosmythe(at)cox.net
Guest

Posted: Mon Nov 27, 2006 4:53 am Post subject: Low spot in fuel system

Tom,

    Didn't you post a pic a couple days ago showing your shutoff valve??? 

If so, the one thing I noticed is your shutoff valve looks like the one that 

caused a big stir on the list about 10 years ago.  It looks like the same 

one that came with my kit.  If I remember correctly, it's a round brown 

plastic material with a center round rotating sleeve.  Leak protection is 

supplied by an "O" ring that is grooved into the curvature of the valve 

body.  Every time you turn the valve the center sleeve rubs the "O" ring. 

Way back, somebody had that "O" ring get cut and it ended up in the fuel 

line toward the carbs.  Engine Out.  A big discussion followed and I ended 

up throwing that supplied valve in the trash and going with a ball and seat 

type valve.  Also, I seem to remember that old valve having a very very 

small inlet/outlet hole for fuel.  The supplied alum tubing had a very small 

I.D.  I upgraded the valve and line to 1/4".

    I've never seen the panel tank installation and wondered how it 

worked???  BTW, I got my kit in September 95.



Don Smythe

---

Lynn Matteson

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

Posted: Mon Nov 27, 2006 4:54 am Post subject: Low spot in fuel system

Why not do away with the supplied shutoff valve and install a valve(s) 

where you want it/them, taking into consideration the downhill flow 

recommendations.



Lynn

On Sunday, November 26, 2006, at 10:31  PM, Tom Jones wrote:



 	  Quote: 	
		   



 Don,

 My Classic 4 did not come with a header tank for behind the seat.  I 

 wish it would have, then I would not need the gascolator.  I purchased 

 the gascolator as an option to install in the low point of the nose 

 tank fuel system.



 For what its worth, the wing tanks feed the nose tank instead of a 

 header tank.  It looks like I may have purchased my kit just before 

 you did.  I should have waited then maybe I would have received the 

 good header tank system.



 The problem I have run into is there is no way to plumb the fuel lines 

 into the shutoff valve where it is designed to go and still have a 

 continuous down hill flow.



 Tom Jones





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=77165#77165

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

eskflyer(at)lvcisp.com
Guest

Posted: Mon Nov 27, 2006 5:28 am Post subject: Low spot in fuel system

Tom

My kitfox 2 has the panel tank and a 13 gallon right wing tank . I also use 

a gascolator on the lower right hand engine side of firewall . I replaced 

the valve in the cockpit with a 3 way vlave left posititon is panel tank 

middle is off and right is wing tank , I also have a valve on the wing tank 

at the root where it comes into the plane . I have never had a problem with 

it this way . the old setup really was terrible when trying to fill the 

front tank and not let it overfill . All fuel drains downhill in my setup. 

in preflight turn on wing tank and drain gascolator for a minute then turn 

on front tank and drain for a minute. works great .

I love my front 9 gallon. Just wish I had my other 13 gallon tank in the 

left wing already .



Take care fly safe fly low fly slow fly fun fly KITFOX

John Perry

lcfitt(at)sbcglobal.net
Guest

Posted: Mon Nov 27, 2006 7:22 am Post subject: Low spot in fuel system

Tom,



I wonder if there is a problem here.  First; though, when I purchased my kit 

in 1993, the panel tank was standard with the aft mounted header tank as an 

option.



The rear mounted header tank has several downward then upward runs of fuel 

line to the shut off valve and engine moun ted fuel pump.  Mine is moounted 

high behind the baggage sack like the I trough III.  Fuel line runs from 

near the bottom of the tank down along the door bottom and then up to the 

valve then down again to the gascollator then up again to the fuel pump.  I 

do have an aux fuel pump at the header tank outlet, but have run the 

airplane in all phases with and without the pump and there is no difference 

in engine performance.



Lowell

---

Tom Jones

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

Posted: Mon Nov 27, 2006 1:52 pm Post subject: Re: Low spot in fuel system

Okay, I have gotten a lot of good comments.



Don, the fuel valve I have is not the one Service Bulletin #42 addresses about leaking.  The fuel line is 5/16ths (OD) aluminum.  However, I do remember the flap about the valve on the kitfox List way back when.  I never could determine what the part number was for the valve they were talking about.



Lynn, I have considered moving the valve but I cannot find a better spot (with a down hill slope all the way from the tank to the gascolator) for it.



Lowell, is your 4 a classic or model 4 1200.  My theory is:  My Classic 4 was one of the first Classic 4's and was caught in a transition period of phasing into the behind the seat header tank.  I got stuck with the panel tank.



I have done some checking with a level today.  With the tail on the ground the fuel valve is level with the tank outlet.  With the plane level the fuel valve is five inches above the tank outlet and the bottom two gallons in the nose tank are below the fuel valve level.



I wrote in my builder's log during my fuel flow tests the nose tank drained completely with the plane in a nose high attitude.  I guess I better do another flow test with the plane level to find out if those bottom two gallons are useable.



John, I also have a 13 gallon tank in  the right wing.  I have a left wing tank on the shelf in the shop.  I figured 36 gallons was over kill for the little Kitfox.  I like your setup with the three way valve.  I am going to give that some serious consideration.



Thanks for the ideas everyone,

Tom Jones

Guy Buchanan

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

Posted: Mon Nov 27, 2006 2:50 pm Post subject: Low spot in fuel system

At 07:21 AM 11/27/2006, you wrote:

 	  Quote: 	
		  The rear mounted header tank has several downward then upward runs of fuel

line to the shut off valve and engine moun ted fuel pump.


	


My poly header tank is mounted as low as possible on the aft side of the 

seat bulkhead. At 3-point rest, (taildragger,) all fuel lines run 

continuously down-hill to the header tank, with the exception of the filter 

which is mounted horizontal and can therefore trap some water. (I thought 

about moving it to the firewall, but decided to fly it this way first. I 

wasn't sure I wanted it in the hot environment.) In flight the line drops 

about 4" from the header to the floor near the control column, then starts 

climbing toward the pulse pump on the firewall. My system will, therefore, 

trap any water coming from the main tanks in the header tank, but might 

also trap water in the filter downstream of the header, coming from I don't 

know where. I'll have to give stronger consideration to moving the filter 

so it is vertical.

Guy Buchanan

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

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

lcfitt(at)sbcglobal.net
Guest

Posted: Mon Nov 27, 2006 3:33 pm Post subject: Low spot in fuel system

Tom,



My airplane is a Model IV-1200 which came out in 1992 just after the Model 

IV-1050.  The Classic IV was reintrocuced much later after Ed Downs returned 

to Skystar replacing Ray Caldwell who had cancelled the Model IV-1200 during 

his tenure as SS President.  You may have the IV-1050 if it has the panel 

tank.



Lowell

---

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