Do I need to file tax returns in USA while living in UK?

It depends. £9,000 today is equal to roughly $14,400. (It will be a different exchange rate at the end of the year, but let's use this as a rough guide). Have a look at the chart on the bottom of page 3 under "filing status" on the following site:
http://www.irs.gov/pub/irs-pdf/p54.pdf
Determine which 'filing status' you fall under. (Are you single and under 65? or over 65 and a qualifying widow? for example) If $14,400 is higher than the threshold for your given filing status, then there's a chance you will have to file a tax return.
 $14,400 is far above the FBAR threshold of $10,000, so yes, you would have to file an FBAR.

Thanks so much for the info.  Makes so much sense now

i have a question guys! I've lived in the UK since 2010 - I filed taxes for 2010 and 2012 - but I made a stupid mistake and somehow skipped 2011. I'm going back to the States for the first time since moving to the UK in 3 weeks. Will I run into any trouble at customs?? Is there any reason for me to run into problems?

I will be filing my 2011 taxes on Monday, but I'm just mailing them in. As I don't meet the requirements for having to pay anything to the States, I shouldn't owe them any money.

Also, just fyi I came to the UK on a marriage visa, now on ILR.

Any help is appreciated

i have a question guys! I've lived in the UK since 2010 - I filed taxes for 2010 and 2012 - but I made a stupid mistake and somehow skipped 2011. I'm going back to the States for the first time since moving to the UK in 3 weeks. Will I run into any trouble at customs?? Is there any reason for me to run into problems?

I will be filing my 2011 taxes on Monday, but I'm just mailing them in. As I don't meet the requirements for having to pay anything to the States, I shouldn't owe them any money.

Also, just fyi I came to the UK on a marriage visa, now on ILR.

Any help is appreciated

I'm assuming you are entering on a valid US passort, so unless there is a warrant out for your arrest I don't think you will have a problem, and I'm pretty sure that one missed tax filing, as recently as 2011, will not have resulted in a warrant for your arrest.

Enjoy your trip back

thanks very much durhamlad! yes i'm entering on a valid us passport and everything is in order in that respect. i never, ever owe any taxes so it's not like i owe the government.

do they issue warrants for people who don't file?

thanks very much durhamlad! yes i'm entering on a valid us passport and everything is in order in that respect. i never, ever owe any taxes so it's not like i owe the government.

do they issue warrants for people who don't file?

I think you would have to owe the IRS a LOT of money in back taxes for a long time before they would actually issue a warrant for tax evasion.