I am playing FTB Academy with a few extra mods. Every time I light the portal it puts its self out after a few seconds of staring at a black thing in it, which could be the portal, but its black.

If you've added Glenn's Gases, then it's this issue: trentv4/GlennsGases#4
Otherwise, it's probably some other mod removing the portal right after it was placed (the black thing is there while it's searching for a suitable location). I recommend starting by removing NetherPortalFix which touches nether portal behavior but doesn't do anything useful as BP doesn't suffer from the issue it's trying to fix.
Having a look at the logs might also prove helpful.

Thank , I am running NetherPortlFix, so I remove it, thank you. If it works this issue will be closed.

I also had this bug and removing journeymap fixed it