Hi Alan,
Do I detect a Garmin 900 here? Mine (IO-550N, G900) sets off a warning bell every time the fuel pressure goes below 8 psi -- it's a real nuisance.
Your current situation sounds like my airplane has always behaved. At 12000 ft, 2300 rpm, 25 LOP, WOT=18.8", I get 9.8gph and fuel pressure below 8psi -- even if I turn on the boost pump. I can get stable fuel flow without the boost pump in this condition, fuel press approximately 7.5psi, so that's the way I fly. No adverse effects. Have done this in straight, cruising flight in smooth or light chop conditions; haven't tested maneuvers or heavy turbulence.
At this flight condition when I have briefly leaned further than 25LOP, the fuel flow has been unstable without the boost pump.
Charley Brown Grand Prairie, TX Legacy #299 N550KC 130 hr
On Jul 5, 2012, at 2:44 PM, Alan Crawford wrote:
Just started having a change in fuel
pressure at cruise. I have a Legacy ... 550N ... been cruising 40 to 60
degrees lean of peak with no problem, with fuel pressure above 8.2 psi.
Depending on altitude 2500 rpm - 2300 rpm ... 11.5 to 11.8 gph ...
The last few flights I can not get 40
degrees lean of peak at any altitude without the fuel pressure dropping below
8.0 psi ... even if I turn on the fuel pump to low = 9, 500 - 11,500 -
12,500 ????
any ideas on what is going on????
Takeoff fuel pressure is 28.0 psi ....
Thanks ...
Alan Crawford
Lake Buchanan, Texas
Lancair Legacy
Life is NOT a journey to the grave with the
intention of arriving safely
in a pretty and well preserved body, BUT
rather to skid in
broadside,
thoroughly used up, totally worn out, and
proclaiming,
"WOW, WHAT A RIDE!!!"
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