Starting new C172s

Newps wrote:

I do the same thing with my Bonanza except the mixture stays full rich.
Starts every time, hot or cold. Why pull the mixture out?

Hey, NewPS, congratulations on your new Bonanza. When did you pick it up?


--
Peter
























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On a cold fuel injected engine, I've always pushed the mixture and throttle
full
forward, hit the boost pump long enough to get needle movement on the fuel
flow
or fuel pressure gauge, then retarded the throttle to 1/4" and the mixture
to idle cut off.

Why push the throttle up?

Because if you don't the fuel won't get in there.

I understand throttle cracked (1/4"), but not full.

"Newps" wrote in message
...


john smith wrote:

On a cold fuel injected engine, I've always pushed the mixture and
throttle
full
forward, hit the boost pump long enough to get needle movement on the
fuel
flow
or fuel pressure gauge, then retarded the throttle to 1/4" and the
mixture to
idle cut off.


Why push the throttle up?

Because if you don't the fuel won't get in there.




http://www.avweb.com/news/columns/182085-1.html

/begin excerpt
Injected Engines

Fuel-injected engines don't have an accelerator pump, so pumping the
throttle on one of them does nothing at all but demonstrate ignorance (not
stupidity, which is an entirely different phenomenon) .

Many problems are mitigated with fuel injection, but others are added. Fuel
injection usually puts all fuel right into the intake port (a few, like the
superb Wright R-3350, put the fuel directly into the cylinder). It is
possible for fuel to run down the "log runner" intakes on flat engines and
create some of the above hazards and problems, but it's far less likely.

Fuel injection is great stuff. But its major problem is the dreaded hot
start. If you shut down, then re-start within about 15 minutes, or if you
wait an hour, it'll probably start right up and run just fine. But it is
that period of time somewhere in between (30 to 45 minutes after shutdown is
generally the worst) that can drive pilots to drink. Nothing seems to work.
The problem is that the hot engine "cooks" all the fuel in the engine
compartment. It cooks it in the main line coming into the engine-driven fuel
pump, the lines after that, and even the tiny stainless lines going from the
distribution valve to each cylinder. The result is a system just full of
bubbles, and these engines don't run well on bubbles.

The only effective technique for this is to make sure the mixture control is
pulled all the way to idle cutoff (ICO), and then run the boost pump for 30
seconds or so. (On "high" if you have a two-speed pump.) Yes, that's a long
30 seconds, but it needs to be done.

Note added 06/06/02: Later data strongly suggests the boost pump be run on
the highest setting for AT LEAST 60 full seconds, by the clock, and 90
seconds is better.
The electric boost pump is usually located somewhere outside the engine
compartment, and thus has no problems with bubbly fuel. What you're doing
here is to circulate cool fuel into and through the engine-driven fuel pump,
up to the fuel control unit, and then back through the vapor return lines to
the fuel tank. The idea is that when you do crank the engine, the
engine-driven pump will really pump liquid fuel, and not starve on bubbles.
A normal start should result. While cranking, you might need a quick shot on
the boost pump to help the cold fuel get beyond the fuel control unit, and
blow out the lines to the fuel distributor ("spider"), and the tiny lines to
each cylinder. But make sure it's really quick, otherwise you risk flooding
the engine.

Peter R. wrote:

Newps wrote:


I do the same thing with my Bonanza except the mixture stays full rich.
Starts every time, hot or cold. Why pull the mixture out?


Hey, NewPS, congratulations on your new Bonanza. When did you pick it up?

A week ago Friday. Flew off the 10 hours with a couple of instructors
in about a week and now I am experimenting on my own. More than any
Cessna I have flown Bonanza owners are scared to death to get slow with
these planes. You wouldn't believe the number of numbnuts out there who
fly final at 100 mph or more. Right now I can comfortably fly final at
75 MPH although the book speed for my weight is 68 MPH so I have some
more practice to do. A friend has a 1300 foot grass strip near here and
I was able to get in and out of there pretty easy( I need 600 feet to
land and get stopped at 2400 pounds, same distance for takeoff). Turns
out the Bo uses only very slightly more runway than my 182 while having
275 more pounds of useful load, going 50 MPH faster on that extra 55 HP
and while putzing around the local area I am burning 9.5 GPH while
indicating 155 MPH versus a max of about 140 MPH with my 182 burning
about 13. If I'd have known all of this I would have bought one years ago.

john smith wrote:

On a cold fuel injected engine, I've always pushed the mixture and throttle
full
forward, hit the boost pump long enough to get needle movement on the fuel
flow
or fuel pressure gauge, then retarded the throttle to 1/4" and the mixture
to idle cut off.


Why push the throttle up?


Because if you don't the fuel won't get in there.


I understand throttle cracked (1/4"), but not full.



That's what I initially thought too. Experience proves otherwise.

Matt Barrow wrote:


The only effective technique for this is to make sure the mixture control is
pulled all the way to idle cutoff (ICO), and then run the boost pump for 30
seconds or so. (On "high" if you have a two-speed pump.) Yes, that's a long
30 seconds, but it needs to be done.

My hot start technique is all levers full forward. Run boost pump until
pressure reaches its max, this is 5-7 seconds, then turn boost pump off.
Pull throttle all the way out and then back in about two turns.
Start the engine. Always starts on first try.

john smith wrote:
I understand throttle cracked (1/4"), but not full.


I open the throttle full before I hit the boost pump to allow a maximum amount
of fuel in to support starting. After it's primed, I only open it 1/4" so that
it won't start up at full bore. It takes a few moments for the oil pump to get
the oil moving so for the first moment or so you have only what oil is clinging
to parts from before.

That's my thinking, anyway. All I can say for sure is that the procedure has
started a lot of engines for me over the years.



--
Mortimer Schnerd, RN

VE

Newps wrote:

You wouldn't believe the number of numbnuts out there who
fly final at 100 mph or more. Right now I can comfortably fly final at
75 MPH although the book speed for my weight is 68 MPH so I have some
more practice to do.

I do believe it, as I bought my Bonanza from one such pilot. During my
transition to the Bonanza and just after I bought the aircraft, he and I
took a flight to a nearby airport. Just after my landing, he tersely
lectured me because the stall warning horn went off just before the wheels
touched down. Apparently he gets very nervous with approach speeds lower
than about 95 kts.

What model did you purchase again?

--
Peter
























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The checklist on the really new (Garmin Glass Panel Equipped) 172S's has
been changed. They now recommend full open throttle while executing the
priming step, then back off the throttle to 1/4 inch per usual before
starting. I understand the change was made because they found that the old
method (as below) was killing batteries with difficult starts.


"OP" wrote in message
...
On 5 Sep 2005 08:40:45 -0700, "navghtivs"
wrote:

I have flown it 6~7 times now, and still find starting the engine of
new Cessna 172S quite tricky, and often I have to try two or three
times to start it. I never had problem in older C172s.

So what's the trick, guys? How much throttle (1/8, 1/4 or 1/2 inch) do
you open? How fast do you advance the mixture when the engine starts to
fire? Anthing else?

Thanks


I rent from a Cessna dealer FBO at VNY. The procedure there is:

Throttle - open 1/4 inch
Mixture - Idle Cutoff
Propeller area - Clear
Master Switch - ON
Beacon - ON
Aux Fuel Pump - ON
Mixture - Advance full - 2 to 3 seconds, then return to Idle Cutoff
Aux Fuel Pump - OFF
Ignition - START
Mixture - Advance full, when engine fires

Works every time for me.

BTW... same procedure when the engine is hot - EXCEPT - Mixture -
advance full - 1 second, then return to Idle Cutoff.

Ron Kelley

On Wed, 07 Sep 2005 08:07:26 -0600, Newps wrote:


I do the same thing with my Bonanza except the mixture stays full rich.
Starts every time, hot or cold. Why pull the mixture out?

Mainly because I'ma thinking the 170-twice in question has a
RSA/Bendix/TCM/Precision fuel injection system opposed to your Bo's
TCM classic fuel injection system.

SOP with a RSA/B system is crank with the mixture at ICO until the
engine fires. SOP for a TCM classic sytem is full rich.

Was in Vero Beach a few years back talking to a long-time TCM factory
engine rep that was getting a lot of compaints about Seneca V starting
issues.

Reminded him that the TCM engine (newly equipped with RSA/B injection
in the Seneca V) needed to be started like a fuel-injected Lycoming...

TC