Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml@lancaironline.net
Date: Mon, 12 Jan 2004 19:01:29 -0500
Message-ID: <redirect-2929590@logan.com>
From: Tubamanflies@aol.com
Subject: Re: [LML] Re: Fuel Transfer Pumps
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In my fuel injected Lancair I also pull directly from the wing tanks, however 
I do not have a header tank.  Each tank is selected with a single valve.  
Left, Right and Off. I swithch tanks every 30 to 45 minutes. There are a couple 
of issues that you have to be aware of when you pull fuel directly from the 
wings. Make sure the engine driven pump will develope good pressure and run the 
engine without a hickup.  The one that was on my engine must have sat around 
for a while before it was used.  It would not develope good pressure all the 
time and the engine would stumble.  A new pump fixed the problem.  You also need 
a boost pump as a backup. You have to be careful about leaks.  Because you are 
"pulling" fuel out of the tanks, air leakes into the fuel system will be hard 
to find.  The engine will not run very well with air in the fuel.  I chased 
an air leak problem for a while until I found the leak was in the boost pump 
seal.  Air was comming in the seal vent even with the pump off.   A good test 
for air leaks is to run a clear tube from the engine pump discharge or pressure 
sender back the tank.  Run the boost pump.  If you see air bubbles start 
looking.  

Finally good baffles in the wing tanks and anti backflow flappers on the 
ports will keep the pickup point from drawing air.   

Ray

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<HTML><FONT FACE=3Darial,helvetica><HTML><FONT  SIZE=3D2 PTSIZE=3D10 FAMILY=
=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0">In my fuel injected Lancair I also=20=
pull directly from the wing tanks, however I do not have a header tank.&nbsp=
; Each tank is selected with a single valve.&nbsp; Left, Right and Off. I sw=
ithch tanks every 30 to 45 minutes. There are a couple of issues that you ha=
ve to be aware of when you pull fuel directly from the wings. Make sure the=20=
engine driven pump will develope good pressure and run the engine without a=20=
hickup.&nbsp; The one that was on my engine must have sat around for a while=
 before it was used.&nbsp; It would not develope good pressure all the time=20=
and the engine would stumble.&nbsp; A new pump fixed the problem.&nbsp; You=20=
also need a boost pump as a backup. You have to be careful about leaks.&nbsp=
; Because you are "pulling" fuel out of the tanks, air leakes into the fuel=20=
system will be hard to find.&nbsp; The engine will not run very well with ai=
r in the fuel.&nbsp; I chased an air leak problem for a while until I found=20=
the leak was in the boost pump seal.&nbsp; Air was comming in the seal vent=20=
even with the pump off.&nbsp;&nbsp; A good test for air leaks is to run a cl=
ear tube from the engine pump discharge or pressure sender back the tank.&nb=
sp; Run the boost pump.&nbsp; If you see air bubbles start looking.&nbsp; <B=
R>
<BR>
Finally good baffles in the wing tanks and anti backflow flappers on the por=
ts will keep the pickup point from drawing air.&nbsp;&nbsp; <BR>
<BR>
Ray</FONT></HTML>

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