Flower drop question

I am growing a few chilies that were refusing to set any fruit.  Any ideas on what I can do?
 
I have a Trinidad scorpion Butch T that is 3 years old, it has hundreds of flowers that I thought were dropping.  On the weekend I had a closer look.  All the flowers up top are dropping but some that are hidden and protected seem to be setting.  What is the deal with this?
 
I also have a 2 year old pineapple rocoto that has been flowering constantly since the first week of January and has only set its first fruit now, but it has also stopped putting out any new flowers.  Any ideas how I can make it produce more pods?
 

For me there was a few factors preventing fruit set..

1. PH of feed water was too high at 8.05. I now adjust it to 6.5 and I believe this has helped.

2. Use high quality potting soil that retains some moisture but drains excess moisture well.

3. Keep out of extreme sunlight.

4. Feed balanced nutes 3-1-2 works great.

And in some cases it does just take ages of flower drop before suddenly producing loads of pods.

Hope some of this helps as I've had the same troubles last season.

Flower drop probable causes:
 
1. Day temp too high >95F
2. Night temp too low <65F or too high >85F
3. Too much nitrogen fertilizer
4. Too much water
5. Low light levels (reduces fertility).
6. Very low humidity (reduces fertility)
7. Poor air circulation (air circulation contributes to pollination).
8. Lack of pollinating insects.
9. Size of pot
10. Too much mineral in feedwater.
11. Too much grower attention/anxiety.