Hot and flooded engine starting.

[Mhutton]

Hi, I am a new member. I purchased my DA40XL used at the end of September 2011. Enjoying the airplane, but am finding it hard to start when hot and then flooded. I am getting conflicting information on starting under these circumstances. Would like to know what other DA40 owners are doing to get the engine cranked.

[Jean]

Welcome to DAN Matt.
Fuel pump OFF, power half inch, mixture cut off, crank, mixture full rich when firing.
We never encountered any problem for warm start and no flodding engine issue so far.(Belgium temperatures are not tropical though !).

[Chris]

Fuel pump OFF, power half inch, mixture cut off, crank, mixture full rich when firing.
We never encountered any problem for warm start and no flodding engine issue so far.(Belgium temperatures are not tropical though !).

Same here. If the engine was running recently and you run the fuel pump for more than a second or two, then it will probably flood and you will end up cranking longer than necessary.

[Rick]

Same here, too. I NEVER use the fuel pump if the engine is hot. I generally open the throttle a bit more when hot, maybe 2-3". Always starts right off.

[hookem80]

Agreed, roughly half throttle, no boost pump and mixture idle cutoff. Don't come in with the mixture until you know the engine is firing. Works every time for me.

Trey

[Chris]

Agreed, roughly half throttle, no boost pump and mixture idle cutoff. Don't come in with the mixture until you know the engine is firing. Works every time for me.

Just be ready to pull back on the throttle immediately if you open it up that much. It does seem to catch more quickly that way, though.

[Tim H]

My question is what is considered "hot"? When do I use the hot starting procedures vs. the cold starting procedures? Do I use the hot if I've been shut down for 1/2 hr, 1 hr, 2 hrs? I know it's dependent on OAT and engine temp, but what is the cutoff point?

[Brichards]

Certainly if the airplane has flown in the last 45 to 60 minutes, priming is not required. Due to the potential for vapor lock, I turn on the boost pump, but do not open the mixture until the engine fires. After a hot restart, I have noticed that my engine runs smoother if I leave the boost pump on during taxi.

[Antoine]

Hello Matt and welcome here. I wish you many pleasant and safe flight hours in your XL.

Adding to the above advice, I would like to give you my experience of flooding and subsequent starts.
If flooding happens, you are probably causing yourself unnecessary misery, just as I did in the beginning... by following the AFM.
Here what real life taught me:

An engine that is not "cold" (did not run today) should be treated as a warm engine.
And in general, it is far better to prime too little than too much. A failed start only results in a second attempt.

COLD START
Follow the AFM procedure.

"NOT COLD" START
When the engine is "not cold", even after a two hour pause, I recommend the following:

Throttle 1/2 inch open. Aux fuel pump on, mixture cutoff.
Check parking brake engaged and stand firmly on brakes.
Crank engine and smoothly/slowly push mixture forward until it fires.
Push mixture slightly further until idle stabilizes then reduce throttle swiftly to 1200 RPM.
Lean engine further and reduce throttle again.
This works 99% of the time for me.

HOT START
When the engine is definitely very hot, I do the same but the first time without engaging the aux fuel pump. Vapor lock may occur as pointed above, but I'd rather risk that than a flooded engine.

FLOODED ENGINE
Managing a flooded engine is a case of keeping calm and taking the time.
Shut down completely, open throttle completely and wait for a minute or two. You may even notice fuel dripping from the left side of the engine. The wide open throttle will help the highly volatile AVGAS go away naturally.
After that, follow AFM. Keep calm and take time before starting again if it fails.
Remember you have limited battery energy and you should not waste it on an engine that is so soaked it can't possibly make the sparks.

GROUND OPS

I have found out that it is very desirable to lean the engine on the ground, in order to avoid fouling the spark plugs. I lean enough to see the EGT bargraphs at the bottom of the instrument. This also increases the heat generated and reduces the warmup time.
In cold weather I lean as much as possible while staying smooth at low revs. I use 1200 RPM most of the time as "idle" and between 1100 and 1400 during taxi.

SPARK PLUGS

Do your plane and yourself a favour and have thin-wire plugs installed at the next plug replacement opportunity. They are worth the money. Smoother, better start and (I think) more power.

Voila! Good flying

[Mhutton]

Thanks all for the help. I do believe most of my problem is operator error.