When the refueller comes around,get him to put 10L in the aux tanks,if the main tank lines are blocked for any reason,you can have a few mins on the aux to sort it out.
If you turn the boost pumps on as soon as the engine starts you will not see if the engine driven fuel pumps are working.
I have seen this happen,one engine was indicating 17psi,but went to 35psi with boost pump on,not good in an electrical
failure.