Bkdoss
Engines starts without fuel pumps but there will be ECAM warning. There was an incident when both engines were started with fuel pumps off and ECAM warnings were cleared without even noticing the warning. Crew climbed to FL380 when both engines flamed out. They relit engines and landed back. You do not seem to understand gravity feed limitations. Descent is made to 150 to prevent vapour lock, you do not climb to 150. Lower is better. Read my earlier post.