I've got that same plastic header tank in my junk pile. It can work but tended to leak evidenced by the fuel stains on it. I think it was used on older model 3/4s.

My KF3 had a round aluminum header tank behind the instrument panel. It had a pump that could feed it and a shut off valve at each wing tank. Sometimes that header tank wouldn't fill w/o the pump esp. on take off. The vent tube back up to the right tank was clear with a red ball in one segment so you could see whether or not gas was in it. This all worked but you had to think about fuel management. The current design is *much* better.

As others have said the problem with the pictured arrangement is that there isn't a good way for the header tank to fill and and the air to cycle back up to the main tank. There should be one line from each of those 3 ports. One each to the outlet of the left and right tank. Last one up to the side vent on the right tank.

Best would be to replace it with the current aluminum tank that mounts low behind the right seat.

My 2 cents,

Mark Napier