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Date: Tue, 24 Jun 2014 15:46:58 -0400
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Subject: Re: [LML] Rough idle in Lancair 360
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From: Berni Breen <bbreen@cableone.net>
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Kevin, yes I had a very rough running IO360 engine in my Lancair whenever th=
e engine was hot and I was on the ground.  This condition would only occur a=
t the end of a flight during taxi.  As you mentioned, these tightly cowled a=
irplanes 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, i=
nstalling 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 b=
ought all of the stuff I needed from aircraft spruce.
Hope this helps=20

Berni Breen
Sent from my iPhone

> On Jun 23, 2014, at 7:27 PM, Kevin <cloudsurfer835@gmail.com> wrote:
>=20
> Hello fellow Lacairians,
>=20
> I've been dealing with a rough idle problem on a Lycoming IO-360-B1B in a L=
ancair 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
>=20
> After having 4 mechanics look into it and spending thousands of dollars, t=
he problem remains. So far, we have put on a new fuel servo, new injectors, n=
ew 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?
>=20
> One last anomaly that might be worth noting since it has now happened twic=
e. During climb out on two hot days, fuel pressure began fluctuating (+/- 5 p=
si), but then stabilized in level flight at higher airspeeds. Once again, tu=
rning on the boost pump had no effect. Perhaps another indicator of a possib=
le vapor lock issue? =20
>=20
> Any advice would be greatly appreciated!
>=20
> Thanks,
> Kevin
>=20
>=20
>=20
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