Backed up kitchen sink is draining to outside and down into crawl space. There is no water in the cabinet under the sink. The sink does not clear, but does eventually drain... down to crawl space (subfloor is pretty saturated) and outdoors apparently. Plunging does nothing.

Side note, a few months back we had a sump failure and after replacement of the pump, I found that the drain line from the sump is blocked. I rerouted that line and have not done anything to open it to date.

Is it possible that the same drain line from the sump pump as the kitchen sink/disposal is blocked? That said, the pump line goes out of the house and into the ground whereas the kitchen drain line goes down to crawl space and then cuts across the length of the house.

Forgive me if anything seems obvious... I am simply trying to learn and DIY it

Unless it's something I haven't run into in the last 50 years the sump discharges out on the lawn or in a ditch while the sink discharges into a drain line to the septic tank or the sewer. The way I read it you have a "S" trap that drains to the floor and not into your wall. Correct?
Your blockage will be found below and downstream from the trap. Remove the trap and send a snake down into the floor until you can hit the clog. Good luck, Tom

I'm with Tom on this. Sump pumps and kitchen sinks are not on the same line, legally that is. An S trap is no longer allowed by most codes for several reasons, primarily siphonong and allowing sewer gas to enter the sink/home.

Thank you, Tom, for your speedy response. The drain DOEs go into the wall and then down to the crawl. Again, the inside of the sink cabinet is bone dry. I have a couple pictures of both the under sink and crawl where it is saturated if needed... I didn't see where I could upload them.

I sure was hoping my logic was off... it just seemed coincidental that there was another block on the same side of the house, I need to find out how to unblock that as well!

Should it mean anything to me that there is some what appears to be a small amount of dried gunk on the drain pipe as it exits the floor into the crawl and the disposal doesn't work all that well?

Many thanks for your time!

Thank you... that makes better sense.

OK, no S trap here but you still need to remove the trap and rod straight into that horizontal pipe in the wall

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I will attempt that in the am... stay tuned and thank you!