I've had a similiar problem. Pumpkins are cucurbits and do have male and female
flowers. It is very easy to distinguish the two. The males are just a slender
flower sprouting from a stem and the females
flower sit on top of a "ball" (embryonic fruit), that comes out of the stem. You may try hand-pollinatining, just take a q-tip or small brush and rub the inside of the male
flower and then immediately rub onto the insides of a female
flower. I usually just pick the male
flower and pull off the petal and then rub that all over the inside of the female. I don't know if you will have enough time left in your season for fruiting though. But if you're just looking for info, then that isn't a concern.
Also, with your
seeds coming from a jack o'lantern you run the chance of the
seeds being hybrid. Since pumpkins are cucurbits they can cross with other cucurbits: zucchini, squash, cucumbers, gourds, and of course, other types of pumpkins. A lot of these combinations may not be viable crosses. Meaning that some of these cross may not germinate,
flower properly, or be able to set fruit.
I think the latter is what has happened with my
seeds. It's just a messed-up cross. It's very irritating to have a 25 foot vining pumpkin with nothing on it.