The first step in waterproofing a foundation crack is by locating the crack. Be careful, water could be entering the basement elsewhere and patching the crack may not solve the problem. Excavate to the footing. If it is 4 feet or less, no problem, but an 8 foot crack will need a backhoe.
Once dug, examine the drain tile if there is any. If clogged, clean out with a hose or in this case I had to use a roto rooter type snake.(note: This type of black flex pipe can be easily damaged when cleaning. I prefer the 4" pvc perforated schedule 35. By splicing into the tile it gives you shorter runs to clean.
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Clean the wall around the crack and Widen the crack to about 1/4" wide and fill with 100% silicone. Apply asphalt primer to the wall, about 12" on both sides of the crack. This will allow good adhesion. Torch down sheet rubber like rubberroid again about 2' wide centered over the crack and lapped onto the footing. Add a sheet of Styrofoam over the rubber to protect it.
Now repair the drain tile if it was defective and add a cleanout to extend above grade for future use. If this area of the yard is low and always wet now would be the time to install a sump pump. Also you can see the counter flashing that I installed to shield the membrane from water wicking down the wall.
Add 6" of clean 1" gravel and filter cloth if draintile has been installed(to act as a leach field)
One of the most important things to to is tamp the back fill. layer in 6"-8" if hand tamping or 12" if using a power tamper. Tamping will help prevent the soil from settling creating a new problem down the road. Add your fill up to grade. Make sure to keep the soil a minimum of 6" below wood siding and 4" below brick.
Rake out from the house making sure everything is draining away from the wall and add seed, fertilizer and straw. If you toss in some annual rye grass seed it will germinate faster allowing your other seed mix ti take hold.