2003 Cooper s- fuel filter replaced, now no start
 

I recently replaced my fuel pump.everything worked fine and I decided to change the fuel filter yesterday. I changed the filter and put everything back together and now the car won't start. I filled the gas tank and double checked all the o-rings but still no start. The car turns over but no start. My first thought was fuel pressure but I'm lost at this point

Did you disconnect the battery? If you did it could possibly just be the computer having to relearn itself and trying to find a base idle.

check the fuel line at the fuel filter verify it has a good o ring

Yep you might not have a good seal on the oring.

I had same thing
 

I forgot to reconnect fuel pump because the wire plug is underneath and so not visible. Check you reconnected yours. You may also have air inside. After new pump installed you should turn ignition only on and off 10 times for the fuel to prime the lines....then start engine. Key in push button key out maybe 6 times. Then start as normal.