Have lush foliage on Porter Improved Tomatoes and little to no production. The blooms are slow to develop into fruit. Green tomatoes are slow to ripen. Bell peppers have same problem.

What are you using to fertilize?
How much?
How often?

Here are a few thoughts:
Maybe you have overfertilized and are creating lush vegetation, but no fruiting?
Have you seen bees?
Are they in a protected spot from wind and aren't self-pollinating? You could hand pollinate, if so.

Also, you don't say where you are from, the temperature range could not be right for fruiting? Or, if you are somewhere that has had a long string of gray days, flowers will fall without fruiting.

Good luck, let us know more!

Fertilization could be a cause for my problems. I added kelp to my beds in late winter and I think it was unnecessary. I garden at Lake Brownwood TX. Our temperatures have been erratic for almost a year. Even in May we had 46 degrees at night and 94 by 10 am. I used floating row cover which really helped to even out the temps. Thanks for your reply.