I have put 200 hours on my 912ULS since my first flight 1.5 years ago. Although the engine only has 200hrs on it, the engine was manufactured almost 5 years ago. I started getting low fuel pressure (1.4psi) sporadically on climb outs at full power. I figured it was either 1) clogged fuel filter 2) bad sender or 3) bad fuel pump. Because the low pressure only happened at full power on climb out, a bad sender didn't seem likely. I checked the gravity flow rate and it was above 12gph so it wasn't a clogged filter. Replaced the fuel pump and the problem was solved. Over 20 hours on the engine since replacing the pump and the pressure always stays right around 3.8psi under all power settings.

I took the old fuel pump apart and the rubber diaphragm seemed to be in excellent shape so I found nothing that could explain the low pressure. I would have felt better had I found something wrong with it. The fuel pump is on 5 year rubber replacement list. I guess the moral is that replacing the fuel pump before the 5 years might be a good idea and also that it's 5 years from the date of manufacture, not 5 years from the date of first use.

As an aside, the time and weight of my electric boost fuel pump was well worth it. Even though I experimented and the engine kept full power with low fuel pressure, it was very re-assuring to know that I had my finger on the boost pump for "plan B".