In a message dated 9/4/2005 12:42:35 P.M. Central Standard Time,=20 olsen25@comcast.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I just=20 finished my annual condition inspection of my 320 and went out for the pos= t=20 inspection first flight. No luck! Engine start was just fine b= ut=20 after a few moments the fuel pressure began to drop from the normal 23psi=20= to=20 the mid teens and lower and then the engine began stumbling. Turning= on=20 the electric boost pump (Dukes) brought the pressure up to 24psi right awa= y=20 and things ran just fine.

Turn the boost off and pressure would beg= in=20 to drop again. I went through this drill a few times with the same=20 results. During one of the times the boost pump was one it just stop= ped=20 running. I toggled the pump switch a few times with no luck. T= hen=20 a few moments later it began running again just fine. I've been unab= le=20 to get it to fail since.

Some background data:
- Engine h= as=20 175hrs since new
- Dukes pump was replaced about 2 flight hours=20= ago=20 (1 month) with a new one
- No header tank
- L/R fuel=20 selector
- Dukes pump located on floor under passenger=20 seat

After doing a bunch of searching through the archives, it soun= ds=20 like several of you have had problems with air leaks in the Dukes pump cau= sing=20 the same problems I am seeing. I won't be able to look at it again f= or a=20 couple of days but that will be the first point I check. Pretty=20 disappointing if this is the problem and it is only 2 hours old and cost=20 $660!

Here's my unique question: Does the Dukes pump have some inte= rnal=20 over pressure switch inside it that could have caused it to stop running f= or a=20 few moments?

Any other advice that can be offered would be greatly=20 appreciated.

Assuming the condition inspection took a week or so, air could have ent= ered=20 the system during the down time. Have you rechecked all the fuel lines= you=20 opened in order to install the pump? If the boost pump is seeing air,=20= it=20 will cavitate (same with the engine pump) and certainly sound different than= =20 when pumping fuel against a closed throttle body with the mixture at id= le=20 cut-off. Also, check the electrical connections you made to insta= ll=20 the new pump - a bad or corroded connection might lead to flaky behavior.&nb= sp;=20 I certainly would be concerned with the pump not running at all..... =20

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)