Dual pmag hot start settings with fuel injection

[thinkn9a]

Looking for recommendations on sequence and settings for hot start, with dual pmags and fuel injection.

With just a couple tries so far, i have failed to come up with the magic combination.

My starter and battery thank you.

[N941WR]

What engine do you have, compression ratio, sparkplug & gap, what timing are you running, and what fimware version is on the P-mags? If your P-mags are installed properly, they should help with hot starts.

Finally, what starting technique are you using?

Check you PM's.

[Bevan]

Also, procedure makes a difference should you have a purge valve or not.

Bevan

[miyu1975]

My technique

Feet on brakes
Half throttle
Mixture full off
No priming
Fuel pump off

Start cranking and slowly add mixture once she starts to fire up.
Adjust throttle as needed

Worked every time.

[tommylewis]

my technique for a hot start is same as Ryan only I set the throttle to about position that gets me about 1200 rpm, works every time

[GalinHdz]

This is how I do it FWIW.

Throttle open 1"
Mixture full rich
Fuel pump on until you hear a distinct change in pump noise
Leave fuel pump on
No prime
Start as normal
When engine catches then throttle to idle (1000rpm)
Works for me every time

This is shown at: https://m.youtube.com/watch?v=7n_zwFfsQjs

[maniago]

As I remember from the Lycoming class, the issue is that the injectors bleed down into the intake manifold over time - like 20mins or so. So regardless of anything else, you have a rich puddle of fuel that you are trying to ingest. So what you don't want or need is more fuel. What you do need is enough air to whip up the puddles and give you something ignitable and of course a thumping good spark to blow though it. Pretty assured your pmags fit that bill.

Again from memory, its mixture off, no prime, crack the throttle, twist until it lights then mix full and throttle to desired. You don't have to slam them home to keep it running. There's usually enough fuel lying around to keep it lit for a good 2 or 3 secs of 1000rpm, which is plenty of time really.

This is what we do in the Citabria and it works as advertised.

[David-aviator]

Originally Posted by maniago

As I remember from the Lycoming class, the issue is that the injectors bleed down into the intake manifold over time - like 20mins or so. So regardless of anything else, you have a rich puddle of fuel that you are trying to ingest.....

Which is why the purge valve in AFP's injection system makes good sense. When the engine is shut down there is no fuel in the flow divider to the injectors to bleed down.

Hot start (for me) is run fuel pump about a minute to circulate relatively cool fuel through the system, set the throttle about a quarter inch, hit the starter and go purge valve knob in and the engine starts right off.

It works for me because it is so simple, I have trouble with systems without the purge valve.

[maniago]

Originally Posted by David-aviator

Which is why the purge valve in AFP's injection system makes good sense. When the engine is shut down there is no fuel in the flow divider to the injectors to bleed down.

Hot start (for me) is run fuel pump about a minute to circulate relatively cool fuel through the system, set the throttle about a quarter inch, hit the starter and go purge valve knob in and the engine starts right off.

It works for me because it is so simple, I have trouble with systems without the purge valve.

I assume that a purge valve means that it just bleeds off the fuel pressure in the divider and lines, right? I assume that the AFP system has a fuel return line then - which the factory Lyc does not.

[Bevan]

Yes, The purge valve needs somewhere to dump the pressure to. Fuel tank is best so you can also circulate fuel back to the tank prior to engine start.

Bevan

Originally Posted by maniago

I assume that a purge valve means that it just bleeds off the fuel pressure in the divider and lines, right? I assume that the AFP system has a fuel return line then - which the factory Lyc does not.