A strange richness...

[Jay Honeck]

On our flight to Nevada, I was impressed with the smoothness and
car-like predictability of Jim Burns' start-up technique with his
Lycoming IO-540s. Jim had a way to start them that I'd not seen
demonstrated before, which I will describe here:

1. Fuel pump on
2. Electric primer on for (a few?) seconds
3. Crack throttle
4. With mixture at full lean, start cranking
5. Gradually enrichen the mixture until the engine fires

(I may have some of this wrong, as the Aztec has nearly every switch
and gauge in bizarre, usually invisible locations...)

By using this method, his engines both started without cranking or
coughing, just like my Subaru.

So, of course, I've been experimenting with this method, which is quite
different than the one described in my POH. (Which basically says
"crank at full-rich"...) It has worked perfectly several times,
especially on hot starts, until yesterday.

Yesterday, after a short stop for a piece of pie ala mode at a nearby
airport, I primed a few pumps, cracked the throttle, and started
cranking with the mixture at full lean. I slowly enrichened the
mixture until the engine caught...at which point it ran VERY rough, and
did not want to stay running.

This condition continued until I LEANED the mixture back, at which
point everything returned to normal. I was able to slowly enrichen
back to full rich, with no further difficulty. Mag checks were normal,
and the flight home -- after a very careful and prolonged run up -- was
normal.

What happened here? Why did this technique induce an over-rich
condition? Theories, anyone?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Ronnie]

Jay,

I also fly a C Model Aztec and use the same technique
to start the engines. In my experience, the engine needs
no priming via boost pump when hot, and you need to let
the engine fire and run for a couple of seconds before
begining to open the mixture, or you end up flooding the engine.

I used to wonder if the engines needed priming or were flooded
when hot. I've learned through experience that in my case, they
are always on the verge of being flooded when hot.

Ronnie

"Jay Honeck" > wrote in message
oups.com...
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires
>
> (I may have some of this wrong, as the Aztec has nearly every switch
> and gauge in bizarre, usually invisible locations...)
>
> By using this method, his engines both started without cranking or
> coughing, just like my Subaru.
>
> So, of course, I've been experimenting with this method, which is quite
> different than the one described in my POH. (Which basically says
> "crank at full-rich"...) It has worked perfectly several times,
> especially on hot starts, until yesterday.
>
> Yesterday, after a short stop for a piece of pie ala mode at a nearby
> airport, I primed a few pumps, cracked the throttle, and started
> cranking with the mixture at full lean. I slowly enrichened the
> mixture until the engine caught...at which point it ran VERY rough, and
> did not want to stay running.
>
> This condition continued until I LEANED the mixture back, at which
> point everything returned to normal. I was able to slowly enrichen
> back to full rich, with no further difficulty. Mag checks were normal,
> and the flight home -- after a very careful and prolonged run up -- was
> normal.
>
> What happened here? Why did this technique induce an over-rich
> condition? Theories, anyone?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>

[Ronnie]

Jay,

I also fly a C Model Aztec and use the same technique
to start the engines. In my experience, the engine needs
no priming via boost pump when hot, and you need to let
the engine fire and run for a couple of seconds before
begining to open the mixture, or you end up flooding the engine.

I used to wonder if the engines needed priming or were flooded
when hot. I've learned through experience that in my case, they
are always on the verge of being flooded when hot.

Ronnie

"Jay Honeck" > wrote in message
oups.com...
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires
>
> (I may have some of this wrong, as the Aztec has nearly every switch
> and gauge in bizarre, usually invisible locations...)
>
> By using this method, his engines both started without cranking or
> coughing, just like my Subaru.
>
> So, of course, I've been experimenting with this method, which is quite
> different than the one described in my POH. (Which basically says
> "crank at full-rich"...) It has worked perfectly several times,
> especially on hot starts, until yesterday.
>
> Yesterday, after a short stop for a piece of pie ala mode at a nearby
> airport, I primed a few pumps, cracked the throttle, and started
> cranking with the mixture at full lean. I slowly enrichened the
> mixture until the engine caught...at which point it ran VERY rough, and
> did not want to stay running.
>
> This condition continued until I LEANED the mixture back, at which
> point everything returned to normal. I was able to slowly enrichen
> back to full rich, with no further difficulty. Mag checks were normal,
> and the flight home -- after a very careful and prolonged run up -- was
> normal.
>
> What happened here? Why did this technique induce an over-rich
> condition? Theories, anyone?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>

[Ronnie]

Jay,

I also fly a C Model Aztec and use the same technique
to start the engines. In my experience, the engine will
be flooded if you run the boost pumps when hot; When
not, it needs no priming. In addition, you need to let
the engine fire and run for a couple of seconds before
begining to open the mixture, or you end up with the
engine flooded even with no prime.

I used to wonder if the engines needed priming or were flooded
when hot. I've learned through experience that in my case, they
are always on the verge of being flooded when hot.

Is your Pathfinder fuel injected?

Ronnie

"Jay Honeck" > wrote in message
oups.com...
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires
>
> (I may have some of this wrong, as the Aztec has nearly every switch
> and gauge in bizarre, usually invisible locations...)
>
> By using this method, his engines both started without cranking or
> coughing, just like my Subaru.
>
> So, of course, I've been experimenting with this method, which is quite
> different than the one described in my POH. (Which basically says
> "crank at full-rich"...) It has worked perfectly several times,
> especially on hot starts, until yesterday.
>
> Yesterday, after a short stop for a piece of pie ala mode at a nearby
> airport, I primed a few pumps, cracked the throttle, and started
> cranking with the mixture at full lean. I slowly enrichened the
> mixture until the engine caught...at which point it ran VERY rough, and
> did not want to stay running.
>
> This condition continued until I LEANED the mixture back, at which
> point everything returned to normal. I was able to slowly enrichen
> back to full rich, with no further difficulty. Mag checks were normal,
> and the flight home -- after a very careful and prolonged run up -- was
> normal.
>
> What happened here? Why did this technique induce an over-rich
> condition? Theories, anyone?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>

[BTIZ]

You "primed a few pumps", I take it this means throttle pumping (accelerator
pumps?) on an already hot engine? I'd guess you did over prime and then
flood the engine.. I am not sure of your engine but I presume it is also an
IO-540? Always follow the POH or manufactures recommendations for your
aircraft or configuration, the Aztruck may not have the same throttle body
or injectors that you have.

On our Pawnee O-540, 250HP, no "injection", on a warm engine, one throttle
pump with the mixture full rich and back up to 1/2 throttle, left mag on and
hit the starter, starts in two blades reduce power and bring the right mag
online. I always shut down with mixture to idle cut off. Others tend to
prefer to run at idle and kill the mags for engine shut down, then they
touch nothing on restart but mags and starter, and it starts right up. I've
also seen raw fuel drain from the carb on their shut down technique.

On the Seneca II, the "book procedure" (cold engine) is mixture full rich,
throttle to 1/2. Electric primers to stabilize fuel pressure (about 4
seconds), release the primer and hit the starter, very smooth start. I've
found at higher airport altitudes and within an hour of landing, engine
still hot, this can tend to over prime or flood the engine very easily. But
then it's to the "flooded engine check list".

I had one airplane that was always hard to start... so when in doubt, flood
it and then do the flooded engine start.. worked every time.. because at
least then you knew what you were dealing with.

BT

"Jay Honeck" > wrote in message
oups.com...
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires
>
> (I may have some of this wrong, as the Aztec has nearly every switch
> and gauge in bizarre, usually invisible locations...)
>
> By using this method, his engines both started without cranking or
> coughing, just like my Subaru.
>
> So, of course, I've been experimenting with this method, which is quite
> different than the one described in my POH. (Which basically says
> "crank at full-rich"...) It has worked perfectly several times,
> especially on hot starts, until yesterday.
>
> Yesterday, after a short stop for a piece of pie ala mode at a nearby
> airport, I primed a few pumps, cracked the throttle, and started
> cranking with the mixture at full lean. I slowly enrichened the
> mixture until the engine caught...at which point it ran VERY rough, and
> did not want to stay running.
>
> This condition continued until I LEANED the mixture back, at which
> point everything returned to normal. I was able to slowly enrichen
> back to full rich, with no further difficulty. Mag checks were normal,
> and the flight home -- after a very careful and prolonged run up -- was
> normal.
>
> What happened here? Why did this technique induce an over-rich
> condition? Theories, anyone?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>

[Denny]

With my Super Viking, Continental IO520-D, I used a similar method to
Jim's... Was able to hot start within 3 blades 99% of the time... And
likewise, you couldn't slam the mixture to full rich or it would flood,
you advanced it gently feeling the engine getting smoother or rougher
as you went and reacting appropriately... Also flew a D model Aztec
heavily during those years.. Same method, same results... Once you
know your engines you can almost 'feel' how much or how little to
prime... Flooding the engine and then pumping down is the most likely
way to run down the battery, melt the solder in the starter, and leave
the pilot in a swearing heap, so of course it is the recommended method
in the POH...

denny

[[email protected]]

: On our Pawnee O-540, 250HP, no "injection", on a warm engine, one throttle
: pump with the mixture full rich and back up to 1/2 throttle, left mag on and
: hit the starter, starts in two blades reduce power and bring the right mag
: online. I always shut down with mixture to idle cut off. Others tend to
: prefer to run at idle and kill the mags for engine shut down, then they
: touch nothing on restart but mags and starter, and it starts right up. I've
: also seen raw fuel drain from the carb on their shut down technique.

In general, it's a bad idea to use the throttle pump to "prime" an engine.
The accelerator pump squirts a surprisingly robust stream of raw fuel straight up
(assuming carb-on-bottom-of-oil-pan arrangement). Unless the engine is being cranked,
that fuel will *immediately* drip straight back down to the carb, do no good for
priming, and create a fire hazzard under the cowling. On a quick-turn with a hot
engine (O-360 in my case), I'll do the throttle-pump (once or twice), but ONLY while
cranking the engine. The squirt of the accel pump presumably will hit the bottom of
the oil pan, partially atomize, and get sucked into the cylinders. Even that is not
as fast/reliable as the primer, which injects directly at the intake valve on all
cylinders.

...just food for thought. Whatever floats your 'scope.

-Cory


************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Jim Burns]

I agree with Ronnie and Denny, hot starts in the Aztec do not require any
priming.

I showed this method to one of our partners the other day and he was happily
surprised at how easy it started. It's simply a matter of obtaining the
correct mixture for combustion, hot/thin air requires very little fuel, add
fuel and the mixture is too rich. The "fuel pump on, then off, full open
throttle, full lean mixture, crank until your battery, starter, patience are
all worn out" POH method simply sucks. It also recommends starting the left
engine first (carry over from when only the left had a generator) but we
usually start the right first, it's closer to the battery, then we've got an
alternator to help the battery send adequate amps through the 20 some feet
of aluminum cable over to the left engine. The POH is usually the "bible"
but when the airplane changes and the POH doesn't, it can really muck you
up.

I typically can tell when the engines are about to fire, then I begin
advancing the mixture, but not too fast or it will kill the engine. It's a
matter of feeding the engine just enough fuel so the engine driven fuel pump
can keep it running.

The flight school that I used to work with had an Archer that students
routinely had trouble starting, they flooded it continually. They'd come
back into the office saying that "they did the hot start method, then
flooded method, now it barely cranks." I'd show them that when hot, it
started best with the mixture pulled back about 1/2 way, not as the POH
advised.

One thing that aggressive ground leaning can teach is just how lean a hot
engine will run. After a flight, while you're taxiing in, lean the engine
so it will barely run, then enrichen slightly. Make a note of where the
mixture lever is. The engine should start when hot at this same mixture
setting without flooding.

YMMV but once you learn the engine it won't vary very much.

Jim

[Dave Butler]

Jay Honeck wrote:
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires
>
> (I may have some of this wrong, as the Aztec has nearly every switch
> and gauge in bizarre, usually invisible locations...)
>
> By using this method, his engines both started without cranking or
> coughing, just like my Subaru.
>
> So, of course, I've been experimenting with this method, which is quite
> different than the one described in my POH. (Which basically says
> "crank at full-rich"...) It has worked perfectly several times,
> especially on hot starts, until yesterday.

.... but your engine is carbureted, is it not?
.... and Jims' are fuel-injected?
.... and Jim's POH specifies this starting procedure?
.... and your POH specifies a different procedure?

I question the wisdom of copying someone else's starting procedure just because
it works well on their engine.

If you have the same engine, well, nevermind.

Dave

[Matt Barrow]

"Jay Honeck" > wrote in message
oups.com...
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires

Works on the TCM IO-550 including the TN version.

BTW, If the mixture is already full rich, how do you enrich it further?

--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

[Matt Barrow]

"BTIZ" > wrote in message
news:1ti3g.8790$Qz.8436@fed1read11...
> You "primed a few pumps", I take it this means throttle pumping
> (accelerator pumps?) on an already hot engine? I'd guess you did over
> prime and then flood the engine.. I am not sure of your engine but I
> presume it is also an IO-540? Always follow the POH or manufactures
> recommendations for your aircraft or configuration, the Aztruck may not
> have the same throttle body or injectors that you have.

Quite! Pumping the throttle on a FI engine serves absolutely NO PURPOSE.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

[Jim Burns]

Matt,
There's a little confusion in this thread.
Jay's engine is a carbureted O-540, mine are IO-540's. You are correct, no
need to "pump" the throttle of a FI engine, no accelerator pump. I also
agree with the comment made about only pumping the throttle of a carbureted
engine while cranking.
Jim

[Jay Honeck]

> You "primed a few pumps", I take it this means throttle pumping (accelerator
> pumps?) on an already hot engine? I'd guess you did over prime and then
> flood the engine.. I am not sure of your engine but I presume it is also an
> IO-540?

Nope. Pumped the primer a couple of times. (The little
Coleman-lantern-style-thingie)

The engine is a normally-aspirated O-540.

I obviously flooded it, but I don't quite understand how this can be
so, simply by starting with the mixture at idle/cut-off, rather than at
full rich.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jim Burns]

My guess, and it's just a guess, is that you flooded the primed cylinders
while the remaining cylinders fired and operated normally, thus the
roughness.

As you advanced the mixture, the primed cylinders continued to be flooded
but the non-primed cylinders operated normally, albeit at a possibly rich
mixture.

As you retarded the mixture, the primed cylinders were then able to
completely burn the leaner mixture and clean themselves up.

Jim

"Jay Honeck" > wrote in message
oups.com...
> > You "primed a few pumps", I take it this means throttle pumping
(accelerator
> > pumps?) on an already hot engine? I'd guess you did over prime and then
> > flood the engine.. I am not sure of your engine but I presume it is also
an
> > IO-540?
>
> Nope. Pumped the primer a couple of times. (The little
> Coleman-lantern-style-thingie)
>
> The engine is a normally-aspirated O-540.
>
> I obviously flooded it, but I don't quite understand how this can be
> so, simply by starting with the mixture at idle/cut-off, rather than at
> full rich.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>

[ktbr]

Jay Honeck wrote:
> Nope. Pumped the primer a couple of times. (The little
> Coleman-lantern-style-thingie)

I never use the primer when the engine is even just warm.
In fact, the O-540 on my Comanche cranks right up with no
priming even after several days of sitting. I usually only
need to prime on cold days, which isn't many in southern Georgia.

If it hasn't flown for a couple of weeks and won't fire up
after a few cranks then I might pump it once or twice.

[[email protected]]

Starting the Continentals using the book procedures for big
Lycomings works fine.

BTW, the procedure Jay mentions is used for Dukes and
other big injected Lycs.

My experience is that when hot, more than "throttle cracked"
is good. Douches it out more easily if it floods

Bill Hale

[Don Tuite]

On 25 Apr 2006 14:19:47 -0700, "
> wrote:

>Starting the Continentals using the book procedures for big
>Lycomings works fine.
>
>BTW, the procedure Jay mentions is used for Dukes and
>other big injected Lycs.
>
>My experience is that when hot, more than "throttle cracked"
>is good. Douches it out more easily if it floods

My O-540 experience is, if you're going to start it hot, shut it down
with the mag switch and don't prime at all.

Don

[john smith]

Are Aztec engines Continentals or Lycomings?
Continentals sometimes have a fuel return line.
I do not know if Lycomings do, also, but I have not seen one that does
on any of the aircraft I have flown.

[BTIZ]

we only use the manual primer on cold days.. less than 40F and never on a
warm engine

I may have mistyped earlier when I referenced IO- vs O-, yes there is no
throttle pump on the IO-
BT


"ktbr" > wrote in message
...
> Jay Honeck wrote:
>> Nope. Pumped the primer a couple of times. (The little
>> Coleman-lantern-style-thingie)
>
> I never use the primer when the engine is even just warm.
> In fact, the O-540 on my Comanche cranks right up with no
> priming even after several days of sitting. I usually only
> need to prime on cold days, which isn't many in southern Georgia.
>
> If it hasn't flown for a couple of weeks and won't fire up
> after a few cranks then I might pump it once or twice.

[Jay Honeck]

> My guess, and it's just a guess, is that you flooded the primed cylinders
> while the remaining cylinders fired and operated normally, thus the
> roughness.
> As you advanced the mixture, the primed cylinders continued to be flooded
> but the non-primed cylinders operated normally, albeit at a possibly rich
> mixture.
> As you retarded the mixture, the primed cylinders were then able to
> completely burn the leaner mixture and clean themselves up.

This makes as much sense as anything -- thanks.

I probably shouldn't have used the primer at all, but it was in that
goofy, "in-between" length of time, where the engine wasn't really
still "hot" -- but it wasn't really "cold" either.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Ronnie]

Lycoming IO-540C4B5 on the non-turbo models.

"john smith" > wrote in message
...
> Are Aztec engines Continentals or Lycomings?
> Continentals sometimes have a fuel return line.
> I do not know if Lycomings do, also, but I have not seen one that does
> on any of the aircraft I have flown.

[Dylan Smith]

On 2006-04-26, Jay Honeck > wrote:
> I probably shouldn't have used the primer at all, but it was in that
> goofy, "in-between" length of time, where the engine wasn't really
> still "hot" -- but it wasn't really "cold" either.

I've found on all the carburetted engines I've flown behind - priming is
only needed if the engine is absolutely stone cold. Even if the plane
has been just sitting in the sun and not flown in 3 days, the warmth of
the sun is enough that priming isn't usually needed.

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

[Travis Marlatte]

I've got an IO-360 and I have always used the crank at lean procedure. In
fact, I crank at full lean until it fires. I don't open the mixture until I
get some sort of bark from the engine.

When hot, no priming. Works every time. I fly an amphib so being able to
reliably start - even when hot - is very important to me since I could be
drifting toward obstacles after pushing off from a dock.

I tend to underprime. I would rather prime a little, try to start, prime a
little more, start. I find this more reliable than overpriming and then
trying to clear the engine.

The only time I have not been able to start is when I primed a hot engine.

--
-------------------------------
Travis
Lake N3094P
PWK


"Jay Honeck" > wrote in message
oups.com...
> On our flight to Nevada, I was impressed with the smoothness and
> car-like predictability of Jim Burns' start-up technique with his
> Lycoming IO-540s. Jim had a way to start them that I'd not seen
> demonstrated before, which I will describe here:
>
> 1. Fuel pump on
> 2. Electric primer on for (a few?) seconds
> 3. Crack throttle
> 4. With mixture at full lean, start cranking
> 5. Gradually enrichen the mixture until the engine fires
>
> (I may have some of this wrong, as the Aztec has nearly every switch
> and gauge in bizarre, usually invisible locations...)
>
> By using this method, his engines both started without cranking or
> coughing, just like my Subaru.
>
> So, of course, I've been experimenting with this method, which is quite
> different than the one described in my POH. (Which basically says
> "crank at full-rich"...) It has worked perfectly several times,
> especially on hot starts, until yesterday.
>
> Yesterday, after a short stop for a piece of pie ala mode at a nearby
> airport, I primed a few pumps, cracked the throttle, and started
> cranking with the mixture at full lean. I slowly enrichened the
> mixture until the engine caught...at which point it ran VERY rough, and
> did not want to stay running.
>
> This condition continued until I LEANED the mixture back, at which
> point everything returned to normal. I was able to slowly enrichen
> back to full rich, with no further difficulty. Mag checks were normal,
> and the flight home -- after a very careful and prolonged run up -- was
> normal.
>
> What happened here? Why did this technique induce an over-rich
> condition? Theories, anyone?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>

[Viperdoc]

I also have an AEIO-540 in my Extra, and the starting procedure is:

Mixture full rich
Throttle full forward
Run electric boost pump for a few seconds
Idle cut off
Throttle cracked
Crank
Mixture forward

Starts every time, hot or cold, and this is with a lightweight starter and
pretty small battery.

Sounds pretty similar.

[nrp]

O-320 in a 172M

When cold using closed throttle - Minimum prime (maybe 1), check
compression of all 4 cyls, roll the airplane out, then 1/2 shot on
initiation of cranking.

When warm - cracked throttle, no prime. It will be appear slightly
flooded.

Burning autofuel, I also shut off the fuel & run the carb bowl dry if
it won't be flown for a week or more. Fresh fuel in the bowl & primer
really helps.

[Jay Honeck]

> Burning autofuel, I also shut off the fuel & run the carb bowl dry if
> it won't be flown for a week or more. Fresh fuel in the bowl & primer
> really helps.

I've run over 6500 gallons of mogas through Atlas, and he (the plane,
that is) was run on exclusively mogas by previous owner(s) for almost
10 years.

I've never heard of what you're talking about before. Are you saying
that mogas starts to go bad after a WEEK?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[john smith]

> I've never heard of what you're talking about before. Are you saying
> that mogas starts to go bad after a WEEK?

Summer gas v winter gas? (different vapor pressures)

http://www.epa.gov/otaq/volatility.htm

Remember that autogas does not have the stabilizers that avgas has.

http://www.chevron.com/products/prodserv/fuels/bulletin/aviationfuel/8_ag
_perf.shtm

http://www.chevron.com/products/prodserv/fuels/bulletin/aviationfuel/11_a
g_refining.shtm

www.eaa.org/education/fuel/autogas_vs_avgas.pdf

http://www.avweb.com/news/maint/187232-1.html

http://www.generalaviationnews.com/editorial/articledetail.lasso?-token.k
ey=8901&-token.src=column&-nothing

[nrp]

Jay Honeck wrote:

> I've never heard of what you're talking about before. Are you saying
> that mogas starts to go bad after a WEEK?

If I don't purge the float bowl, starting cold w mogas is less
predictable, and a bigger slug of fuel will puddle and remain in the
intake manifold after startup. This slug goes thru the engine with a
lot of burping & coughing etc as the throttle is first advanced after
starting. I consider this tacky. I don't like flying behind engines
or with pilots that don't start well - just on general principle.

This doesn't happen if the engine is warm as the oil heats the manifold
which minimizes fuel condensation.

Mogas has a wider distillation temp range than a/c fuel. The light
components of mogas will more easily evaporate from the bowl leaving
you with a more-like-kerosene mixture for starting, depending on how
long it has been sitting. Yes you can usually get things going, but it
does mean grinding the starter more.

In the fifties farmers would burn something we called "Powerfuel" in
their carburated tractors. I worked in a garage & we could never get
them going without priming with fresh gasoline.

My lawn mowers like this too. Especially my snow blower. Can aircraft
be far behind?

[Drew Dalgleish]

On 26 Apr 2006 20:48:16 -0700, "nrp" > wrote:

>Jay Honeck wrote:
>
>> I've never heard of what you're talking about before. Are you saying
>> that mogas starts to go bad after a WEEK?
>
>If I don't purge the float bowl, starting cold w mogas is less
>predictable, and a bigger slug of fuel will puddle and remain in the
>intake manifold after startup. This slug goes thru the engine with a
>lot of burping & coughing etc as the throttle is first advanced after
>starting. I consider this tacky. I don't like flying behind engines
>or with pilots that don't start well - just on general principle.
>
>This doesn't happen if the engine is warm as the oil heats the manifold
>which minimizes fuel condensation.
>
>Mogas has a wider distillation temp range than a/c fuel. The light
>components of mogas will more easily evaporate from the bowl leaving
>you with a more-like-kerosene mixture for starting, depending on how
>long it has been sitting. Yes you can usually get things going, but it
>does mean grinding the starter more.
>
>In the fifties farmers would burn something we called "Powerfuel" in
>their carburated tractors. I worked in a garage & we could never get
>them going without priming with fresh gasoline.
>
>My lawn mowers like this too. Especially my snow blower. Can aircraft
>be far behind?
>
Thanks that makes a lot of sense. I've aways found my engine 0-290D to
be harder to start with autoffuel than 100LL even though it runs much
better on it. I amost always have my engine stall after about 20
seconds during a cold start regardless of priming or throttle pumping.

[[email protected]]

: In the fifties farmers would burn something we called "Powerfuel" in
: their carburated tractors. I worked in a garage & we could never get
: them going without priming with fresh gasoline.

My dad's 1939-ish Oliver-60 Row Crop (that he still uses to plow snow and run
the PTO pump for the logsplitter) was one such creature. It would run on either gasoline
or kerosene ("farm-fuel" is what I'd heard it called). That tractor's a hoot to drive
around.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Matt Barrow]

> wrote in message
...
>: In the fifties farmers would burn something we called "Powerfuel" in
> : their carburated tractors. I worked in a garage & we could never get
> : them going without priming with fresh gasoline.
>
> My dad's 1939-ish Oliver-60 Row Crop (that he still uses to plow snow and
> run
> the PTO pump for the logsplitter) was one such creature. It would run on
> either gasoline
> or kerosene ("farm-fuel" is what I'd heard it called). That tractor's a
> hoot to drive
> around.
>
Through rush hour traffic, no doubt! ;~)

[nrp]

> I amost always have my engine stall after about 20
> seconds during a cold start regardless of priming or throttle pumping.

Can you tell if it is flooding out or starving out? And do you also
get the loping coughing etc after the first throttle advance?

[Drew Dalgleish]

On 27 Apr 2006 11:36:03 -0700, "nrp" > wrote:

>> I amost always have my engine stall after about 20
>> seconds during a cold start regardless of priming or throttle pumping.
>
>Can you tell if it is flooding out or starving out? And do you also
>get the loping coughing etc after the first throttle advance?
>
Pretty sure that it's starving out. No coughing though.

[Denny]

Our tractors have just set around since last fall... We burn the
cheapest, nastiest, mogas we can find... We do not use Stabil, etc...
Drag the battery charger over to the tractor... Give the battery a 5
minute buzz to wake it up from laying around for five and a half
months, jump on, pump the throttle, hit the starter, and away we go...
Dunno why your gas goes bad, mine doesn't...
Now, if you leave the tank nearly dry and let it evaporate down to
sticky crud in the bottom of the tank... Pour fresh gas in, washing the
crud into the carb... Then your gas has gone 'bad'...

denny

[Jay Honeck]

> Our tractors have just set around since last fall... We burn the
> cheapest, nastiest, mogas we can find... We do not use Stabil, etc...
> Drag the battery charger over to the tractor... Give the battery a 5
> minute buzz to wake it up from laying around for five and a half
> months, jump on, pump the throttle, hit the starter, and away we go...
> Dunno why your gas goes bad, mine doesn't...

Same here. We've got a lawn tractor, a leaf-blower, a weed wacker, and
a snow blower. They ALL use mogas that sits for half a year, and we
never have a problem.

To believe that mogas goes bad in less than a month is goofy.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jim Burns]

Same here.
We've got no less than 30 gas powered trucks that sit from October to April
with less than 1/4 tank (gives the thieves less to steal and makes them work
harder for what they get).

Wake up the battery, insert key, choke, crank, start, run.

We also have a 2 - 10,000 gallon tanks for gasoline. They sit from October
to April with less than 2-3 feet in them. By the time spring comes, this
gas is god knows how old since I didn't get a manufacture date on the load
when I bought it the fall before. We run the tanks down to about 1 foot,
then I buy another load. The gas is used in everything from tractors to
trucks to lawnmowers to dozens of small engines. No problems, it simply
works and it's always the cheapest gas that I can find.

Jim

[nrp]

The problem isn't long term cold storage or large quantities. It is
critical small quantities (like a carb bowl) that are heat soaked (like
an airplane) after shutdown. A starter will work its way thru it if it
isn't too bad, but why?

[Jay Honeck]

> Mogas has a wider distillation temp range than a/c fuel. The light
> components of mogas will more easily evaporate from the bowl leaving
> you with a more-like-kerosene mixture for starting, depending on how
> long it has been sitting. Yes you can usually get things going, but it
> does mean grinding the starter more.
>
> In the fifties farmers would burn something we called "Powerfuel" in
> their carburated tractors. I worked in a garage & we could never get
> them going without priming with fresh gasoline.

Well, they must've changed the mix since the 1950s a bit, because I
have never experienced any of the adverse symptoms you describe, in any
internal combustion engine, from tiny 2-strokes, to automotive V-8s, to
aircraft engines.

Or maybe we get better mogas here in Iowa? :-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

Jay Honeck > wrote:
: Same here. We've got a lawn tractor, a leaf-blower, a weed wacker, and
: a snow blower. They ALL use mogas that sits for half a year, and we
: never have a problem.

: To believe that mogas goes bad in less than a month is goofy.

It definately starts to *smell* skunky. Whether or not it makes an appreciable difference after
only one month is another question. For a marginal mogas STC like our O-360 (180hp) and its 91 AKI
requirement it might be easier to evaporate the "high octane" components. For low-compression, it'll
probably run on just about anything.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[nrp]

A suggested bedtime reading (in 4 sections) for history and technical
details of gasoline is here:

http://www.faqs.org/faqs/autos/gasoline-faq/part1/