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To:  lml@lancaironline.net
Date: Sun, 15 May 2011 08:04:47 -0400
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Subject: Fuel restriction or air?
From: Berni <bbreen@cableone.net>
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I have been trying to chase down the cause of a fuel issue in my normally as=
pirated Lancair IV engine.  During a cross country flight my fuel flow indic=
ator began to show fluctuations which I mistakenly believed to be false read=
ings.  Shortly thereafter during the same flight the engine began surging, s=
lightly at first but increasingly worse in short time.  So much so that I be=
gan to plan for an emergency landing as I was looking to find the cause and t=
o introduce a remedy.  I turned on my electric (back up) fuel pump and the e=
ngine immediately began to run strong and the fluctuation readings stabilize=
d. =20

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

My initial take was that my problem was caused by a failing engine driven fu=
el pump.  Even with that belief (once back on the ground) I checked as much o=
f the fuel system as possible looking for potential restrictions.  I looked a=
t and cleaned the screens at the wing root connections as well as the inlet o=
n 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 f=
ine in the air on a subsequent cross country trip.  Approximately 2.1 hours o=
f flying time later the exact same symptoms returned...erratic fuel flow rea=
dings followed closely by engine surge.

I am now at a loss as to what I should now look for.  Could my problem be du=
e 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 possib=
ility?

Any and all suggestions would be most appreciated.

Sent from my iPad
Berni Breen
Bbreen@cableone.net=