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From: Sky2high@aol.com
Full-name: Sky2high
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Date: Mon, 23 Jun 2014 19:37:06 -0400 (EDT)
Subject: Re: [LML] Rough idle in Lancair 360
To: lml@lancaironline.net
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Kevin,
 
Consider that at idle the hot engine driven pump gets no cooling at  all.  
There is no return line so that the boost pump is only marginally  effective 
in raising the fuel pressure - thus reducing vapor "lock".   Consider that 
the exhaust system may be radiating infrared heating to the  pump - one way 
to reduce that effect is to put a SS clamped (at tabs) piece  of raised SS 
blocking radiation from reaching the pump.  Like a motorcycle  exhaust 
shield.   Heat is your enemy.
 
Scott krueger
 
 
In a message dated 6/23/2014 6:27:45 P.M. Central Daylight Time,  
cloudsurfer835@gmail.com writes:

Hello  fellow Lacairians,

I've been dealing with a rough idle problem on a  Lycoming IO-360-B1B in a 
Lancair 360 for way too long. It only happens when  the engine is hot, so 
I'm wondering if anyone else has had this problem and  what, if anything, can 
be done about it.  The engine runs very strong in  flight, and the problem 
only occurs on the ground when hot and at low  RPM.  Turning on the boost 
pump has no effect. The previous owner said he  had the same problem so this 
has been going on for a very long time.  

After having 4 mechanics look into it and spending thousands of  dollars, 
the problem remains. So far, we have put on a new fuel servo, new  injectors, 
new plugs, and checked the timing and ignition system and found no  
problems. I've also subscribed to Savvy Analysts and they can't find anything  
wrong in the engine data. The next couple of things we are going to look at  
(again, but more thoroughly) are both fuel pumps (mechanical and electrical),  
and the fuel flow divider. We are also thinking that there might be an air  
leak somewhere in the fuel system because the boost pump won't prime until 
the  engine is cranked on the first start of the day, but then it boosts just 
 fine.  We are also thinking that we could have a vapor lock problem since  
it only happens when hot, and these are obviously tightly-cowled engines. 
I've  heard from other Lancair 360 owners that many of these planes tend to 
idle  rough when they're hot, so perhaps we've been chasing our tails this 
whole  time and this is something we just need to live with?

One last anomaly  that might be worth noting since it has now happened 
twice. During climb out  on two hot days, fuel pressure began fluctuating (+/- 5 
psi), but then  stabilized in level flight at higher airspeeds. Once again, 
turning on the  boost pump had no effect. Perhaps another indicator of a 
possible vapor lock  issue?  

Any advice would be greatly  appreciated!

Thanks,
Kevin


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<DIV>Kevin,</DIV>
<DIV>&nbsp;</DIV>
<DIV>Consider that at idle the hot engine driven pump gets no cooling at=20
all.&nbsp; There is no return line so that the boost pump is only marginall=
y=20
effective in raising the fuel pressure - thus reducing vapor "lock".&nbsp;=
=20
Consider that the exhaust system may be radiating infrared heating&nbsp;to =
the=20
pump - one way to reduce that effect is to put a SS clamped (at tabs)&nbsp;=
piece=20
of raised SS blocking radiation from reaching the pump.&nbsp; Like a motorc=
ycle=20
exhaust shield.&nbsp; &nbsp;Heat is your enemy.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Scott krueger</DIV>
<DIV>&nbsp;</DIV>
<DIV>
<DIV>In a message dated 6/23/2014 6:27:45 P.M. Central Daylight Time,=20
cloudsurfer835@gmail.com writes:</DIV>
<BLOCKQUOTE=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid">=
<FONT=20
  style=3D"BACKGROUND-COLOR: transparent" color=3D#000000 size=3D2 face=3DA=
rial>Hello=20
  fellow Lacairians,<BR><BR>I've been dealing with a rough idle problem on =
a=20
  Lycoming IO-360-B1B in a Lancair 360 for way too long. It only happens wh=
en=20
  the engine is hot, so I'm wondering if anyone else has had this problem a=
nd=20
  what, if anything, can be done about it.&nbsp; The engine runs very stron=
g in=20
  flight, and the problem only occurs on the ground when hot and at low=20
  RPM.&nbsp; Turning on the boost pump has no effect. The previous owner sa=
id he=20
  had the same problem so this has been going on for a very long time.=20
  <BR><BR>After having 4 mechanics look into it and spending thousands of=
=20
  dollars, the problem remains. So far, we have put on a new fuel servo, ne=
w=20
  injectors, new plugs, and checked the timing and ignition system and foun=
d no=20
  problems. I've also subscribed to Savvy Analysts and they can't find anyt=
hing=20
  wrong in the engine data. The next couple of things we are going to look =
at=20
  (again, but more thoroughly) are both fuel pumps (mechanical and electric=
al),=20
  and the fuel flow divider. We are also thinking that there might be an ai=
r=20
  leak somewhere in the fuel system because the boost pump won't prime unti=
l the=20
  engine is cranked on the first start of the day, but then it boosts just=
=20
  fine.&nbsp; We are also thinking that we could have a vapor lock problem =
since=20
  it only happens when hot, and these are obviously tightly-cowled engines.=
 I've=20
  heard from other Lancair 360 owners that many of these planes tend to idl=
e=20
  rough when they're hot, so perhaps we've been chasing our tails this whol=
e=20
  time and this is something we just need to live with?<BR><BR>One last ano=
maly=20
  that might be worth noting since it has now happened twice. During climb =
out=20
  on two hot days, fuel pressure began fluctuating (+/- 5 psi), but then=20
  stabilized in level flight at higher airspeeds. Once again, turning on th=
e=20
  boost pump had no effect. Perhaps another indicator of a possible vapor l=
ock=20
  issue?&nbsp; <BR><BR>Any advice would be greatly=20
  appreciated!<BR><BR>Thanks,<BR>Kevin<BR><BR><BR><BR>--<BR>For archives an=
d=20
  unsub=20
http://mail.lancaironline.net:81/lists/lml/List.html</FONT></BLOCKQUOTE></D=
IV></FONT></BODY></HTML>
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