first off what type of primer is it??

If it has been sealed tight and in a reasonable climate it will most likly be just fine.

The test... open it up and mix the death out of it...I mean mix and mix and mix OR take it to a paint shop and slip them a few buck's to put it in the shaker

See if there is any chunks in it or any seperation after mixing - if not use it.

If it's a 2k product then get fresh hardener and fresh reducer - Don't use the old stuff!!