You cannot get an FHA loan if you have a defaulted federal obligation (like a student loan) reported in CAIVRS. Getting your loans out of default will clear the entry in CAIVRS and that hurdle to approval.
The second hurdle is your overall credit profile - if the original defaulted tradeline is still on your report (as it would be if you consolidated), or if the lates leading up to the default (these sometimes stick around after rehab) are still there, they could bring down your score below the approval threshold. FHA probably also has guidelines for acceptable numbers of late payments based on how recent they are as well.
The best thing to do is visit with a lender about your particular situation. If you can, take a copy of your credit report and see if they will informally review it and give you a sense of what it will take to be approved.
