Hi Sherilee!
Hmm...
I think he might be a little overtired when he goes down. At 8 weeks you probably want to only keep him up about an hour, maybe a little less, between his last nap and his next. You'll want to save keeping him up an hour and a half when he's between 3-4 months.
Experiment with his window a little bit between 45 mins and an hour. That's probably enough time for feeding, maybe 5 mins of play, and nap routine.
Also, if you haven't already (if you have ignore this paragraph), you might want to create a consistant naptime routine and start it maybe 10 or 15 mins before he's ready to be put down. It doesn't have to be long or really involved, maybe like rocking him before putting him down drowsy but awake. This will help him understand that it's sleepy time.
Let us know how it goes!!
*HUGS*
Sonya =P