Rotax 912 fuel return line

[adam.rigden]

I have a Kitfox 5 Outback with a Rotax 912 UL 80hp. I want to add a fuel return line back to the header tank which from what I have read is the best possible option. My header tank is aluminum, and I have the optional fuel sensor so this port is not available for the return line. Can I "T" off one of the 4 ports for the return line? If so, any suggestions as to which would be the best one? I have been told that if i use the sensor port, I might get erroneous results. If I use the vent line or the fuel inlet ports will I get a "back flow" to either the tanks or up the vent line? I have attached a picture of my current installation. Any input would be greatly appreciated.

[jiott]

I would suggest removing the tank (not a hard job) and welding on a boss for the return port just below the existing sensor port.

[kitfox2009]

Hello Jim
Take this for what it is worth but I would think a tee in the line from the tank side would work OK. I would think there should be less fuel volume/pressure in the return line than what would be in the tank feeder lines. Therefore the fuel should not return to the tank against that flow. Even if it did, why would this matter? The only time I could see the possibility of more fuel returning than being "used" may be at idle with some sort of an auxillary pump running.
I returned the line back to the gascolator and it seems to operate very well. I do not have an auxillary pump.
I am sure more "hydraulics follks" will straighten us out on this one"
Springtime in north america!!
Cheers
Don

[jiott]

You are probably right Don, its just that I personally would not tee into a wing tank line. Its always kind of a issue trying to get both wing tanks to drain equally, and adding more flow squirting in at 90 degrees to one side would seem to me to make the issue worse.

[ofergd]

Best place to place a "T" is at the output port from the tank to the gascolator and engine. You will allways return les fuel than what you pump out when the engine is running.

[adam.rigden]

Thanks for the input. I think I am going to go with the first suggestion to add another port. McMaster Carr has weld on fittings in either 6061 or 5086 aluminum. Which would be more appropriate. I have access to a welder who can do the welding for me.

Adam

[kitfox2009]

No question Adam,that is the more professional approach.
Don

[kmach]

That will work,

Another couple ideas with no welding, is to use the side port where your low fuel warning sensor currently is. You can get a low fuel level sensor that goes into the vent line, or the low level fuel sensor kit from kitfox that has a small tank above the header tank with the sensor in it. Just some more options.

I have my return line going to the side of the header ,where your fuel sensor is. My low fuel level sensor is in the vent line just above the header, I got it from Highwing LLC .

[kmach]

Oh, and we need to see some pictures of your 5 !

[adam.rigden]

Here are a few pics from last fall in my driveway. I am in the final stages of finishing. Hope to have it at the airport this summer. Fuel system, electric carb heat, ELT are the last things to do....