I have one of those small generators from harbor freight. I bet you would burn up the motor on the sump pump with it. It barely will produce enough juice to power a couple of lamps. Then the power fluctuates where the lights flicker and brown out. It wasn't very durable either. I drained the fuel out of it after each time I used it and the thing won't run anymore.
I also have a harbor freight air compressor. It worked alright but didn't last very long. I suppose if a person only aired up a tire from time to time it would work fine but I was using it to operate a nail gun and spray some paint.
I've had real good luck with harbor freight tools with the exception of these two.