I'm not sure that the discharge from the pool has caused the crack.
Nevertheless, since you will be excavating to repair the crack, you will be able to check the status of the weeping system in that spot. It is about 30 years old. Do not be surprised if you find it clogged solid with soil. In that case, it will have been useless for some time.
From what you have described, the best things to do would be:
1. Repair the crack in the foundation as planned. If the weeping system is clogged, leave it alone.
2. Install a yard drain and a pipe to use when you drain your pool, to direct the pool discharge around the house and to daylight on the far side, or to an existing municipal storm drain, if readily available. A 4-inch plastic pipe should suffice.
I'm assuming no water enters the crack in your foundation. That is why I suggest ignoring a clogged weeping system.
You may find that the crack was caused by a tree root, or a rock in the backfill, or hydraulic pressure, but in the latter case, you probably would have gotten water inside the basement. If the crack is almost vertical and located near dead center of the wall, it may be a shrinkage crack; however, if so, the crack would probably have happened early in the life of the house, such as within the first year.
Good luck, and please let us know of your success.
Architect (NY) and Home Designer (PA)