Try gently shaking the plant or hand pollinating. Probably mid morning after the dew dries and flowers are fat with pollen would be the best time. There are some products on the market such as blossom set, that supposed help force the plants to set fruit. Your problem can sometimes be caused by over fertilizing or planting in overly rich soil, which can over stimulate vegative growth at the expense of fruit. Also sometimes the problem occurs early season in the absence of adequate pollinators. The most prominant time for blossoms to drop is when daytime temperatures are well over 90 and night time lows are over 70. Hang in there, you will likely get a good fall crop when the temperatures drop a little.