Rough idle in Lancair 360

Submitted by Anonymous on

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From: Kevin <cloudsurfer835 [at] gmail.com>
Sender: <marv [at] lancaironline.net>
Subject: Rough idle in Lancair 360
Date: Mon, 23 Jun 2014 19:27:41 -0400
To: <lml [at] lancaironline.net>

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

Rough idle in Lancair 360

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Re: [LML] Rough idle in Lancair 360
Date: Mon, 23 Jun 2014 19:37:06 -0400 (EDT)
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

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 [at] 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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Rough idle in Lancair 360

Submitted by Anonymous on

From: Mark Sletten <mwsletten [at] gmail.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] Rough idle in Lancair 360
Date: Tue, 24 Jun 2014 15:45:50 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

It sounds like you've thoroughly checked out the fuel delivery system. What about the ignition system? Perhaps a bad magneto/plug/plug wire that only manifests when hot?

--Mark

On Jun 23, 2014 6:27 PM, "Kevin" <cloudsurfer835 [at] gmail.com

> wrote:

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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Rough idle in Lancair 360

Submitted by Anonymous on

From: Gary Casey <casey.gary [at] yahoo.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: Rough idle in Lancair 360
Date: Tue, 24 Jun 2014 15:46:47 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message
I agree that heat is the obvious culprit, but it sounds like the problem isn't the engine-mounted fuel pump vapor-locking.  If the electric pump has no effect, the problem probably isn't between the tank and fuel servo.  Is the line from the servo to the distributor well insulated?  I like to use the old-fashioned loose-fitting fire sleeve for this as it offers good insulation.  The next thing is to make sure all components are as cool as possible.  There should be a shroud around
the fuel pump with cool air ducted to it.  The gascolator should be isolated from the engine compartment and cooled.  Yes, there is a remote possibility of an air leak causing a problem.  Sometimes air will leak in, but fuel won't leak out.  And sometimes electric pumps are located higher than they could be or are in the engine compartment and therefore run hotter than they should.  In order, I would:
1.  Insulate all fuel lines with fire sleeve.
2.  Duct cool air to the mechanical pump
3.  Duct cool air to the gascolator.
4.  Think about relocating the
electric pump
5.  Look for an air leak

Gary Casey
Hello fellow Lacairians,

I've been dealing with a rough idle problem on a Lycoming IO-360-B1B in a
La=
ncair 360 for way too long. It only happens when the engine is hot, so I'm w=
ondering if anyone else has had this problem and what, if anything, can be d=
one about it.  The engine runs very strong in flight, and the problem only o=
ccurs on the ground when hot and at low RPM.  Turning on the boost pump has
n=
o effect. The previous owner said he had the same problem so this has been g=
oing on for a very long time.=20

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, ne=
w 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 t=
he engine data. The next couple of things we are going to look at (again, bu=
t more thoroughly) are both fuel
pumps (mechanical and electrical), and the f=
uel flow divider. We are also thinking that there might be
an air leak somew=
here in the fuel system because the boost pump won't prime until the engine i=
s cranked on the first start of the day, but then it boosts just fine.  We a=
re also thinking that we could have a vapor lock problem since it only happe=
ns 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 t=
hey'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 ps=
i), but then stabilized in level flight at higher airspeeds. Once again, tur=
ning on the boost pump had no effect. Perhaps another indicator of a possibl=
e vapor lock issue? =20

Any advice would be greatly appreciated!

Thanks,
Kevin

Rough idle in Lancair 360

Submitted by Anonymous on

From: Berni Breen <bbreen [at] cableone.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] Rough idle in Lancair 360
Date: Tue, 24 Jun 2014 15:46:58 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Kevin, yes I had a very rough running IO360 engine in my Lancair whenever the engine was hot and I was on the ground.  This condition would only occur at the end of a flight during taxi.  As you mentioned, these tightly cowled airplanes keep a lot of heat in there and my problem was fuel getting hot  in the fuel pump.  After cutting a 1" hole in the metal baffling at the back, installing a 1" fitting and connecting scat tubing from that fitting down to a shroud I installed enclosing the fuel pump, problem gone.  I recall that I bought all of the stuff I needed from aircraft spruce.

Hope this helps



Berni Breen

Sent from my iPhone



> On Jun 23, 2014, at 7:27 PM, Kevin <cloudsurfer835 [at] gmail.com> wrote:

>

> 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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