Couple of things to check.
1). How much fuel in the fuel can?
2). Is the gasket in the fuel adapter cap fully seated?
3). Did you try re-fueling another MBU, or does the same thing happen?
4). Check the air compressors on the MBU's that will not re-fuel, ensure they are functional.
Good luck, hope that helps
John
1. FULL! probably 4.5 gal (so there is some air space)
2. Yes.
3. Same thing, different MBU
4. Compressors seem fine as they light and function.
Both fueled fine when the cap was off with the hose in the diesel, leading me to believe that this is a suction / vacuum thing on the cap. I even put the scepter on the MKT deck to see if it was a height and head pressure issue. No difference.
It definitely says that the valve will auto open and close on the tag. I still think that's the issue. The other item to note is that my scepters do not have the vent tube on the inside (red arrow), but shouldn't affect anything but volume when pouring, as the hole is still not blocked when on a flat surface (and doesn't affect anything when using the high volume spout). I am wondering if on the drawing below if the cap is overtight and the hole is being blocked (orange arrow) or the vent is not being as automatic as I want. I only fueled two MBU's, which is about all that the scepter could hold, so will have to burn some more diesel or fill the others to check it. I'll mess with it a bit more and report back.
And that pict is not my actual scepter can, just a pict I swiped, so no, I am not using red holders for diesel, or have weird statues in my house.