Some years ago I had an engine stoppage in a Piper Aztec. It was during climbout, shortly after I had shut off the aux pumps. Yes, I had shut them off one at a time. I turned the pumps back on and the affected engine restarted. A bit of troubleshooting revealed that the left engine would stop running a few seconds after I shut off its aux pump, so I terminated the flight, assuming that the engine-driven pump had chosen to take the day off.
This is a companion discussion topic for the original entry at https://www.avweb.com/ownership/whats-under-the-hood-fuel-pumps