It sounds like you may be confusing sewer drains, (inside your house and ultimately connected to the sewer system) and your homes exterior drain tile system. Two totally unrelated systems. If you have a drain outside of your basement slider it is probably connected to the foundation drain tile system and/or terminates into a french drain or empties via gravity if your property layout allows. If your area has had a lot of rain and the ground is saturated would explain why it refills after you try to clear "the clog". You may need to do some investigating to verify. Do your gutter downspouts go into a drain tile? They may also terminate into a french drain type system.
Tim - nuroom