A strange richness...

"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

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

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"

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"

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.

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

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

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.

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.

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"