Engine starting techniques

[SquawkModeA]

Recently had an interesting experience when going flying with a friend. One of the C172's we have down at the club is particularly hard to start. This time we struggled for several minutes before enlisting the help of a nearby mechanic. He explained that the primer only works on one cylinder and this leads to the starting problems. He recommended rapidly pumping the throttle while cranking the engine.

Said technique worked better though the engine was still reluctant to start and while fiddling around with the throttle and mixture lever I realised how little I know about starting engines. Was never taught anything else than two strikes with the primer and the school's planes always started on the first attempt.

Anyway even though it worked out in the end, this whole thing got me a bit concerned, primarily with regards to the risk of fire, as I didn't really know what I was doing when I tried to start the engine. Could anyone enlighten me about the best techniques when the engine doesn't want to cooperate, and also what I absolutely shouldn't do to get it running?

Thanks a lot,

ModeA

[Flik Roll]

Often starting with the Fuel pump in fixed pitch a/c helps, as it does with hot fuel injected a/c.

Fire is most likely to happen if you overprime (depending on where your exhausts are located...) as when you over prime fuel could potentially drip onto hot exhausts.

(would say more but I have to go...sure someone else can finish in better sense and more detail!)

[18greens]

Most failed starts appear to be to do with the throttle being too far open. Too much air, not enough fuel.

An Instructor once taught me just to crack the throttle, (a quarter inch is too much). I've never had a reluctant engine since.

[Scoob]

If you have tried to start it and it wont it is probably flooded. Pull the mixture back to cut off and crank it over till it fires then push the mixture forwards to keep it running.
In injected engines it is often hard to start after a recent shut down. Try running the fuel pump with the mixture cut off for 15 seconds then try to start it.

[Kolibear]

I was taught to start cranking the engine with the throttle closed and then gently open the throttle. When the engine finds its correct fuel/air mixture, she will burst into life.

[Aim Far]

Most failed starts appear to be to do with the throttle being too far open. Too much air, not enough fuel.

That's interesting. My aircraft has a fuel injected engine and, as noted, it is a to start when still hot from a previous flight. But the technique (approved by POH) of using a LOT of throttle with the mixture at cut off while turning it over using the starter then rapidly bringing the throttle back once the engine has caught and the mixture is in seems to work almost every time.

[18greens]

Aim Far, well pointed out . My technique only works with carb engines.

[Jhieminga]

The technique of pumping the throttle to get priming fuel into the cylinders relies on the accelerator pump squirting fuel when the throttle is rapidly advanced. It may have some added value on some engines but I would caution against using it as not every engine will benefit from it. Basically while starting the throttle is an air control, best to use it for that purpose! (applies to a carburettor engine!)

[TD&H]

Engine starting techniques:

Press start button
At 10%+ N2 and with N1 showing
Open HP cock

Seems to work every time

[Windy Militant]

Roll Up Sleeves, spit on hands for traction and swing!

[GJB]

FOR LYCOMING CARB ENGINES:

I've seen so many people pirme, try to start, and if it doesn't fire then start pumping like mad at the throttle, aircraft is reeking of fuel due to over priming and is now in real danger of a fire.

So here is my technique, as demonstrated by a mechanic and it has never let me down since.

COLD STARTING
Prime, Mixture RICH, throttle set 1/4 open and crank. If no joy them stop a mo. Mixture to ICO and close thr throtle. Crank, advance mixture to fully rich. She most often catrches here so swiftly advance the throttle to let her idle. If not, justtweak the throttle to squirt in a bit more fuel butr do not pump at it.

HOT STARTING

Mixture ICO, throttle closed, crank, advance micture to rich. She always catchs here, so just enough throttle to get her idling nicely.

And now for the after starts..........