Sounds like the outer limit screw on the FD needs adjustment out. either that, or the cable is too tight.

Tell us - does the shifter click when shifting into the big ring? If not, then relieve all cable tension and verify that the left shifter clicks up and down properly. If it works ok without cable tension, Then, re-string the cable and turn the adjustment screw out a little bit and try again. Keep doing that until it clicks in to place.