Fuel Flow Stoppage

[rtc183]

I have the low fuel sensor kit from Kitfox and the other day it came on after a long climb. During descent it went out again and I consulted with John and did some troubleshooting. I found that the fuel line that was zip tied to the cross members behind the seat had slid down and caused a kink at the attachment of the left wing line to the collector tank. Didn't think about the line ever sagging since it is fairly stiff and zip tied tightly to the frame. Hope to show this and prevent anyone else from having the same problem. Without the low fuel sensor I would have never noticed until I ran out of gas.
Here are the before and after pics. I used waxed lacing cord to tie it up to the frame on the side and above to keep it from ever going down again.
BobKinkedLine.jpgFixedLine.jpg

[Jerrytex]

Good catch. I am fearful of any zip ties on fuel lines especially on the gravity drops from the wing tanks. Adel clamps are a good option to hold the lines in position to get the straightest, kink free route from the wing tanks to the header tank.

[109JB]

Adel Clamps.

[airlina]

Bob, in your after picture it appears that your left fuel line has a dip in it still that shouldn't be there. You want that line to run continuously downhill from the wing tank to the header. Bruce N199CL

[Kitfox Guy]

Consider replacing the header tank with an aluminum model. I had two plastic header tanks fail me twice.

[rtc183]

This is the aluminum tank. Painted it.
I didn't think the line needed to be straight down to the tank since it is a vented collector tank.
Bob

[Jerrytex]

This is the latest guide from the kitfox build manual.

https://kitfoxaircraft.com/builders-manual/

Page 12 of the final assembly.


Screen Shot 2023-07-04 at 1.23.52 PM.jpg

[Dave S]

I didn't think the line needed to be straight down to the tank since it is a vented collector tank.
Bob

Bob,

Bruce is absolutely correct about this.

The build instructions are pretty clear also. Since the two fuel feed lines from the wings are purely gravity - cavitation and other strange things are a possibility on these lines. The engine fuel pump won't equalize this. Also have the potential for unequal feed from the wings. Both fluids (air and fuel) will take the path of least resistance.

Fuel lines from the wings to header tank should be downhill all the way. Vent line should be uphill all the way to the starboard fuel tank. Liquid=down, air=up.

I found strapping a 1/8" welding rod (or similar) to the longer spans of fuel hose helps keep things organized.

[rtc183]

Thanks for the info and manual reference. Should have looked it up myself. Just had extra hose so I used it. Easy fix.