I went to Vault 3 and the Fiend in the start of the vault told me to go to Motor Runner after I told her I had drugs. I went to Motor Runner and told him the NCR told me to kill him. I killed him and took his helm. I found out it was a quest item but I don't think I have any quest to kill Motor Runner. Is it a bug or what is I'm going to do?

Thanks for now.

There's an unmarked quest. Show the helmet to Colonel Hsu in Camp McCarren.

Make a separate save. Go talk to Colonel Hsu in his office at McCarran and see if the appropriate quest is given. Also talk to Major Dhatri out by the tents.

There's someone to find and people to save in Vault 3...not just the bounty for Motor Runner.

Okay thank you very much. Shouldn't Anders be in Vault 3?

he should be there but i have never seen him there. he will magically appear back at that fort.

Apparently yes, however, every time I exit Vault 3, after offing the druggie, Anders just calmly walks back to McCarran.(and [censored]in' about my involvment)