Thats why you use more, ive only made 2 and im telling you use more !For thirding a 5 gallon batch i used 2 -15 0z cans and it was alot better than the first i did with one 15 oz can in a 1.7 gallon batch. But really its the spice also, just be carfull not to overspice. Dont get preserved pumpkin, i used straight organic pumpkin, any additives will make a poor beer.
I also learned much more up to my second pumpkin batch ( i did quite some time later)so i had that experience going for me to make a better one and it was like a pumpkin brown.I also recommend carmalizing it with a little molassis a little bit.
Have you ever eaten a pumpkin plain to really taste it? Try it sometime. Its really " pumpkin pie" that people think of when thinking of pumpkin and not the plain vegetable.If thats what you want i suggest an amber type malty beer, i like to add some victory or biscuit malt for a crust type effect or even brown malt(which can impart a sourdough flavor) and a little chocolate. Mine ended up being a brown ale though,not shure what your going for.