Starting new C172s

In article ,
says...


The reason given by the FBO was that the fuel flow meter in "some"
of the injected 172's is either slow to respond or doesn't read
accurately at the aux fuel pump flow rate. And it is easier to
flood the engine using the fuel flow meter. Don't know how true
that is, but the timed method (using a simple one thousand, two
thousand count) is accurate enough.



Tha argument for using the fuel flow meter instead of a timed method is
that you don't know if the pump is primed or not, so the time it takes for
X amount of fuel to be pumped, after you flip the switch, is variable.
Your method though works around this, because you leave the pump ON, and
"dose" the fuel with the mixture control. Sounds OK to me. It's true that
it's very easy to flood these engines, and pilots transitioning from
non-injected models will have more trouble with too much fuel flow than
too little.

G Faris

Tha argument for using the fuel flow meter instead of a timed method is
that you don't know if the pump is primed or not, so the time it takes for
X amount of fuel to be pumped, after you flip the switch, is variable.

The Piper Turbo Arrow IV manual contains a time chart based on OAT for
priming.

OP wrote:
The reason given by the FBO was that the fuel flow meter in "some"
of the injected 172's is either slow to respond or doesn't read
accurately at the aux fuel pump flow rate. And it is easier to
flood the engine using the fuel flow meter. Don't know how true
that is, but the timed method (using a simple one thousand, two
thousand count) is accurate enough.


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. Crank the engine and when it catchs, push the mixture to full
rich. Always seemed to work.



--
Mortimer Schnerd, RN

VE

In article ,
ve says...


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. Crank the engine and when it catchs, push the mixture to full
rich. Always seemed to work.



That's standard - but OP is proposing a slightly modified procedure, which
might have some adavantages

G Faris

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?
Throttle controls air, mixture controls fuel.

Mortimer Schnerd, RN 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. Crank the engine and when it catchs, push the mixture to full
rich. Always seemed to work.

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?

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

I've flown about 25 different 172SP's, and they've all behaved exactly
the same.

I open the throttle about an inch, and do the rest exactly by the
checklist. The only important variables seem to be:

- Make as little delay as possible between priming and turning the key
to START. It doesn't need to be immediate, but don't delay
unneccessarily.

- Advance the mixture from IDLE CUT OFF to RICH within a second or so.