surpentine belt on 1993 Plymouth Acclaim

the new surpentine belt keeps coming off every time we start it any suggestions?

Asked by for the 1993 Plymouth Acclaim
I would look at the tensioner as it may have weakened.

make sure all the pulleys are ok and not wobbling from wear,

it had one on there just a few days ago it was weak and making a noise so we are trying to replace it but it keeps slipping off. trying the tension now!! :(