I'm still confused.
It appears from your replies that originaly, the Engine Failure ECAM told me to OPEN (select ON) the X Feed and that this procedure took precedence over the Low Fuel contents ECAM.
So now my ECAM says "Monitor Fuel Imbalance" which apparently means do the imbalance QRH checklist. No where in this check list does it say turn all the fuel pumps on and leave the cross feed open. It asks me to close the X feed when the balance is complete.
As far as I can see, at present, we don't have a published Low Fuel Contents procedure when Single Engine. We seem to rely only on crew awareness.
It appears that the change in the ECAM from "Open X Feed" to "Monitor Fuel Imbalance" has been tripped up by an error in L+R Wing Tk Lo Lvl ECAM procedure. I think the error is the Fuel X Feed should be selected On (Open) not Off (Closed).
What does the A330 Low Fuel Contents procedure say?