Starting new C172s

On Tue, 06 Sep 2005 09:14:49 +0200, Greg Farris
wrote:

In article ,
says...


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.



Pretty close to the standard method - but why use a "timed" method to
determine fuel flow from the pump, when there is an instrument in front
of you that gives precise information? If you didn't have a fuel flow
guage, or suspected that it wasn't working, this would be a good backup
method - but on the ones I've flown this guage is always working, and
gives a reliable indication for the starting procedure.

G Faris

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.

I guess if you are flying your own plane or the same one every time,
using the fuel flow meter would be more convenient once you knew
what the fuel flow meter should read to properly start your engine.
The only place I see a problem would be starting a hot engine.
Apparently you don't want as much fuel in there under that
condition. Maybe that would be a lower fuel flow rate.

Ron Kelley

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

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

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.

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.

Well, you need both for combustion.

.... but the fact is that on this airplane (and most fuel injected
engines, I believe) the fuel won't flow into the engine unless the
throttle is open.

You can easily test this by turning on the aux fuel pump and advancing
the mixture to rich while keeping the throttle fully closed. You'll
sit there all day without seeing the fuel flow meter move.

In article .com,
says...


Well, you need both for combustion.

... but the fact is that on this airplane (and most fuel injected
engines, I believe) the fuel won't flow into the engine unless the
throttle is open.

You can easily test this by turning on the aux fuel pump and advancing
the mixture to rich while keeping the throttle fully closed. You'll
sit there all day without seeing the fuel flow meter move.


Besieds which - even if you get the engine to start with the throttle
closed, you will need to advance it as soon as it starts, necessitating
a third hand.

GF

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?

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.