Fuel pressures
I just replaced my fuel filter as part of routine service. Attempting to bleed with the lift pump, I noticed it was not coming on. I use a fuel pressure gauge setup with a tee with a drain valve on it (common service tool) connected to a clear hose. It makes the air bleed procedure less messy, and I can check the LP pressure at the same time.
In the past week, I experienced a stumble at launch a few times. With engine running, not only was there no pressure at the test port, but a slight vacuum. Power and grounds check solid, I'm ordering a new lift pump today.