Are you sure evil-want-C-u-scroll is set to t? Note that this variable should be set to t before evil is loaded. You may also check which command C-u is bound to (using C-h k C-u, it should be bound to evil-scroll-up). If this does not help, please check if the problem occurs when starting with make emacs from evil's source directory. Does this problem occur in modes other than tuareg? Furthermore, please provide your evil version and Emacs version.
I can reproduce it. Here is my .emacs file https://gist.github.com/vrthra/9999335
with GNU - Emacs 24.3.1
It works fine when I start emacs directly, however, if I use emacs client `exec emacsclient --alternate-editor="" --nw -c file```, it will not work (even when the server is restarted).
I don't know other package managers but when using "el-get" to load evil, it issues a (require 'evil) statement transparently. If your evil-want-C-u-scroll is not set before this, evil will not see the option being set to t.