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Date: Sun, 15 May 2011 20:48:46 -0400
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From: "Bruce" <BGray@glasair.org>
Subject: RE: [LML] Fuel restriction or air?
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Have you checked the screen in the fuel servo?

Bruce
WWW.Glasair.org 

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Berni
Sent: Sunday, May 15, 2011 8:05 AM
To: lml@lancaironline.net
Subject: [LML] Fuel restriction or air?

I have been trying to chase down the cause of a fuel issue in my
normally aspirated Lancair IV engine.  During a cross country flight my
fuel flow indicator began to show fluctuations which I mistakenly
believed to be false readings.  Shortly thereafter during the same
flight the engine began surging, slightly at first but increasingly
worse in short time.  So much so that I began to plan for an emergency
landing as I was looking to find the cause and to introduce a remedy.  I
turned on my electric (back up) fuel pump and the engine immediately
began to run strong and the fluctuation readings stabilized.  

After gaining altitude I turned off the electric pump and the unstable
fuel flow readings as well as the engine surge returned.

My initial take was that my problem was caused by a failing engine
driven fuel pump.  Even with that belief (once back on the ground) I
checked as much of the fuel system as possible looking for potential
restrictions.  I looked at and cleaned the screens at the wing root
connections as well as the inlet on the GAMI injectors.  I found no
restrictions so I removed and exchanged my engine driven pump for a
rebuilt unit.

After installing the rebuilt pump the engine tested fine on the ground
and fine in the air on a subsequent cross country trip.  Approximately
2.1 hours of flying time later the exact same symptoms
returned...erratic fuel flow readings followed closely by engine surge.

I am now at a loss as to what I should now look for.  Could my problem
be due to air somehow being introduced into my fuel flow?  Should I be
looking at my fuel selector as a possible culprit?  If so how would I
test that possibility?

Any and all suggestions would be most appreciated.

Sent from my iPad
Berni Breen
Bbreen@cableone.net
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