Question

How can congress prevent the federal government from a "shut-down" if the fiscal budget process is incomplete?

Answer 1

The way that a congress could prevent the federal govenrment from a "shut-down" if the fiscal budget is incomplete is:  pass legislation known as "stop-gap funding" to keep the government running.
This legislation will freeze all government function for a specific period of time (most commonly no more than 4 month) in order to do a massive budget saving.