uneven fuel flow from tanks? solution?

[wildirishtime]

A buddy and I have noticed the right wings on our model 5's tend to empty long before the left tank. Is there any solution to this?

~Brendan

[Av8r3400]

Check rudder trim, keeping the ball in the center.

Thats what did it for me... :)

[wildirishtime]

Yea it's not our flying or our plumbing, it's all new and all tests conducted in smooth air - and i'm not talking about just a gallon difference, it's usually 3-4 gal different every long haul flight.

Separate valves are a patch, not a solution - it sure seems that for 3 hour flights with level wings they should consume almost exactly the same rate.

Does anyone else have this problem? Or is this within the realm of 'normal' for model 5/6/7 Kitfox for long cruise flights?

[Peteohms]

There is another recent thread on this subject. If one of your gas caps doesn't seal, that might cause it. In my case new gaskets helped. I still have a few gallons different after 6 or so hours, but I can let one tank be empty and the other keeps providing fuel. Probably some minor restriction on one side in my plane. My wife always says my bubble is a bit off. ;)

[airlina]

Yea it's not our flying or our plumbing, it's all new and all tests conducted in smooth air - and i'm not talking about just a gallon difference, it's usually 3-4 gal different every long haul flight.

Separate valves are a patch, not a solution - it sure seems that for 3 hour flights with level wings they should consume almost exactly the same rate.

Does anyone else have this problem? Or is this within the realm of 'normal' for model 5/6/7 Kitfox for long cruise flights?

My Series 5 has always done the same thing,I must admit it gets a little unnerving watching the fuel level in one tank going out of sight on a long cross country. I went for the patch solution and added individual inline shutoff valves in each main line from the tank to the header. I can now control fuel flow from each tank and you get the added benefit of tank to tank isolation for refueling on uneven ground. i have seen many kitfoxes get topped off and when left for an hour on uneven ground fuel pees out the vent of the low tank. By shutting one of these inline valves this situation is eliminated. can be used for maintenance as well. Has been a good fix in my case . Bruce N199CL

[kmach]

Hi,

I also have the inline valves for each wing tank, and right below them I have a glass spectre fuel filter on each line as well.

On occasion I do get the right tank emptying faster, I can see the fuel flow thru the glass filters and use the valves to equal the flow, It usually requires around a quarter turn to closed, on the right wing tank to even the flow.

[wildirishtime]

I also have the same filter/valve installation for servicing the filters and testing my header low fuel switch, but I still don't see WHY the tanks dispense unevenly, or IF there is a solution / modification to get them to flow evenly. I don't like shutting off one tank (fully or partially) as I like the redundancy that both tanks provide into the header.


~Brendan

[kmach]

I have thought of replacing the left wing tank to header line with a larger

diameter line for less restriction (friction loss)of flow ,the current left wing

tank line has a lower angle and longer run with no vent and I think this is part

of the problem.

Thoughts ?

[wildirishtime]

So your left wing is also the slow one? yea mine too. I have 5/16" fuel line at this time.

[kmach]

Yes ,

it is usually the left tank when it happens.

After saying that though, I have had the reverse happen as well, if

circling allot to the left, or flying one wing low for a awhile, so maybe that

kills my previous theory.:confused:

(I usually am flying solo, so maybe a slight right wing high attitude is the cause of the left tank not draining equal?)

On my setup it does not occur every flight, and I think it is something that can be monitored and controlled easily enough, so I monitor it like everything else.:)

[Dave F]

Yea it's not our flying or our plumbing, it's all new and all tests conducted in smooth air - and i'm not talking about just a gallon difference, it's usually 3-4 gal different every long haul flight.

Separate valves are a patch, not a solution - it sure seems that for 3 hour flights with level wings they should consume almost exactly the same rate.

Does anyone else have this problem? Or is this within the realm of 'normal' for model 5/6/7 Kitfox for long cruise flights?


Not sure why you call this a patch- it works well.

If you have all equal in a your fuel system you might be Ok or maybe not.
-gas caps both sealed the same?
-fuel lines the same length and same amout of bends and all bends the same radius?
-is fuel flow exactly the same from each tank the T connector in fuel system?
-is your fuel tank vents equal and calibrated?
- is fuel cap vents the same?
- is everything calibarted equally thought out fuel system?

Separate valves are simple and easy and not necessarily a "patch".

Cessna has the same issues as well. This is not isolated to Kitfox.
You just got to learn to manage your fuel better.

I like to know that I fuel in each tank and when one is low I will switch over.

If you lose a gas cap in flight or have a bad gasket on gas cap you could actually be flying on "BOTH" and have both drain while you fly.