I just finished my annual condition inspection of my 320 and went out for the post inspection first flight.  No luck!  Engine start was just fine but after a few moments the fuel pressure began to drop from the normal 23psi to the mid teens and lower and then the engine began stumbling.  Turning on the electric boost pump (Dukes) brought the pressure up to 24psi right away and things ran just fine.

Turn the boost off and pressure would begin to drop again.  I went through this drill a few times with the same results.  During one of the times the boost pump was one it just stopped running.  I toggled the pump switch a few times with no luck.  Then a few moments later it began running again just fine.  I've been unable to get it to fail since.

Some background data:
  - Engine has 175hrs since new
  - Dukes pump was replaced about 2 flight hours ago (1 month) with a new one
  - No header tank
  - L/R fuel selector
  - Dukes pump located on floor under passenger seat

After doing a bunch of searching through the archives, it sounds like several of you have had problems with air leaks in the Dukes pump causing the same problems I am seeing.  I won't be able to look at it again for a couple of days but that will be the first point I check.  Pretty disappointing if this is the problem and it is only 2 hours old and cost $660!

Here's my unique question: Does the Dukes pump have some internal over pressure switch inside it that could have caused it to stop running for a few moments?

Any other advice that can be offered would be greatly appreciated.

Dan,

 

Assuming the condition inspection took a week or so, air could have entered the system during the down time.  Have you rechecked all the fuel lines you opened in order to install the pump?  If the boost pump is seeing air, it will cavitate (same with the engine pump) and certainly sound different than when pumping fuel against a closed throttle body with the mixture at idle cut-off.  Also, check the electrical connections you made to install the new pump - a bad or corroded connection might lead to flaky behavior.  I certainly would be concerned with the pump not running at all.....