I have a 04 level 2 with a 4.0 I was changing my tensioner pull so I replaced my belt too but once I put it on the belt will not stay on the crankshaft pulley it rides on the front edge . After looking at the fan pulley they are half off so the fan pull y makes the belt ride out of the slot on the crenkshaft???

 

You probably have the belt routed wrong

There should be a diagram on Rad support

Remove the belt and line up the pulleys visually, if the new tensioner is not lined up then it is the wrong one or not installed correctly