Check for rust on the rear lower side of the cab on the driver's side, behind the door.  Some have had a problem there in the states that use salt on the roads.  

I know a retired engineer who holds patents on parts of that fuel system and he owns a similar Ford that he uses to pull a large travel trailer. I would ask him about it for you except he is off on one of his long trips now pulling his trailer somewhere, chasing the fall colors.

Around here, all the farmers always buy Ford trucks including my brother who has worn out more of them than I can count.  But last month he did something different, he bought a new Toyota.  I think it was mostly a matter of price and maybe the aluminum skin.