A puzzlement.... Weather-wise, they should be doing ok.

When the flowers drop, or are near dropping, do they look dry/crispy or limp/soggy?

You said they are planted in pots. In native soil, or in commercial potting soil? And if commercial, what kind?

I can't remember the brand, but it's a potting mix. The flowers do look dry, but only in the way that they dry up normally once pollinated. In other words, they look just like a pollinated bean, then they fall off shortly after. I'm wondering if the pollen is dying from the heat, even though it seems like it shouldn't be.

Also, they are sharing the pot with a tomato plant (it's a big pot though). But the beans don't look stressed in any way so I don't think the tomato is to blame.

Big Mama limas are heat sensitive. They will drop flowers until the temperature drops into the 70's.

DarJones - who has a 120 ft long row of them this year and they have made very few beans.

Oh no! I bought Big Mamas because I read that limas loved the heat and I wanted to try something with big delicious beans. I guess that was a mistake. I wish they'd display that kind of information with the product. Thanks.

Feeding Phosphate rich fertilizer and planty of water may help to solve your problem.