I have Eclipse Luna Release (4.4.0), and I have been using it for years.
For the first time, only on a specific project, the PyDev search doesn't work properly. As an example, if I try to search for the name of a function that I know to be there, it doesn't find it, and there are no typos. This happens for most of the search, even if some of them give the expected result.
The weirdest thing is that if I use the file search then it works. Why is that? Do you know any ways to solve?
In Navigator view, right-click the project name and select PyDev > Set as source folder (add to PYTHONPATH). 
After that I find PyDev search works. Very handy as a quicker search function.
PyDev Search doesn't work properly on Eclipse