OK, so you changed the secondary once. Now that the engine has gone down again, what happens when you change the secondary again? Was the replacement secondary blocked? That could confirm bad fuel...
But if the new secondary isn't blocked, that could instead suggest there's something floating around in that one tank, and whatever that something is eventually finds it's way to the mouth of the pick-up tube.
IOW, I suspect it could be one of two conditions, maybe or maybe not both...
I think.
??
-Chris