1. To begin operating, functioning, or running and produce some sound as a result. The computer started up with a loud whir of its fan. The old car started up with a splutter and a cloud of black smoke from its exhaust.

2. To use some implement in order to cause something to begin operating, functioning, or running. In this usage, a noun or pronoun can be used between "up" and "with." Cars these days start up with the turn of a key, but back in the day they were much harder to get running. You'll need to start the computer up with a special password.

3. To form or set up a business, enterprise, endeavor, etc. with some particular resource. In this usage, a noun or pronoun can be used between "up" and "with." My parents have owned this business for nearly 50 years, starting up with the money given to them as gifts for their wedding. I'm starting up a business with the money

4. To work together with someone to form or set up a business, enterprise, endeavor, etc. In this usage, a noun or pronoun can be used between "up" and "with." I'm starting up a new business with some former colleagues of mine. Do you want to help start up a new social media platform with me? I really think it could turn into something special.