How do i find fuel for the big ship?

Here are something you can try.

1.Rescue Badger's girlfriend from the monsters in the tanker's hold, then ask him to hack the Emperor and transfer the fuel (this results in Badger's death at the hand of Shi enforcers.

2.If your karma, charisma and intelligence are high enough, it is possible to talk to Ken Lee to gain direct access to the Emperor (make sure to save before you talk to him though, because sometimes he will not let you in without doing a quest first). Ken Lee is wearing a lab coat, and can be found in the large, brick layered room with the throne by the entrance of the temple. Once you begin talking to him, tell him directly that you need fuel, and he will mention something to the effect that he can tell that you are a good, trustworthy person, and will then give you the password to the emperor, and tell you that the force field in the next room blocking the Emperor will be disabled. When you actually get into the next room, the force field has not been disabled, possibly due to a glitch, thus you will need to repair the field in order to get by. You will not be attacked if your presence has already been cleared by Ken Lee. Fiddle around with the computer a bit, and the fuel will be transferred to the tanker. This method is preferred if you do not wish to get involved with the Shi's affairs, and want to keep Badger alive.

3.If Ken Lee does not trust you when you ask him for fuel, as menioned in the previous scenario, he will send you on a quest to retrieve Vertibird plans and bring them to Dr. Wonng Yi Tze. Once they are in your possession, bring them to the doctor and then you can get your fuel.

4.Hack the Emperor.

5.Trade a suit of Hardened Power Armor to Dr Jing Tie Gahng in the Steel Palace for fuel.

6.If you are playing on the dark side, killed Badger for Hubbologists and transfered fuel to the Shuttle, there is still a way to complete the quest — hack computer terminal in Dr Jing Tie Gahng's science lab. This should be done before you kill Shi Emperor, otherwise the computer will not work. In this case, your only chance to get the fuel may be to lower your intelligence by using Mentats and then wait for 24 hours. Then talk to AHS-9.