Airflow Performance Hot Start Procedure

[Geico266]

Should the electric fuel pump be on or off? That is the question.

My normal hot start is open the fuel bypass, open throttle & mixture control, turn on pump for 45 seconds to push hot fuel into left tank.
Turn off fuel pump, set throttle to half, mixture to cut off.
Crank til she pops then open mixture, close down throttle to idle.

Another forum talking about the procedure to hot start a FI Aztec said leave the fuel pump on... use the mixture control to shut the fuel off. They do not have the fuel bypass like AFP.
Open throttle 1/3rd and open the mixture full for 2 seconds, then close mixture.
Start till she pops and open mixture.

While both would work, it seems to me having the pump on and opening the mixture 2 seconds would add fuel to the cylinders faster than relying on the mechanical pump that is now heat soaked.

Any thoughts?

[Walt]

Your procedure is correct.. a few things to keep in mind:

Shut down of the AFP system should be with the purge valve.

When hot starting, wait till the engine fires then move the purge valve to "run".

A hot engine will be flooded with fuel from the spyder and lines draining into the cylinders after shutdown, always treat a hot engine re-start as flooded.

If you add more fuel to this by running the pump with the purge valve closed, you will just agravate the situation. The FM200 is not like the Bendix, with the mixture in idle cut-off some fuel will still get by and will flood the motor with the pump running.

[N427EF]

Another successful method to hot start is using the purge valve in the following manner:
Purge the system as you have described but now leave the boost pump
On, Set throttle, mixture rich, start cranking and close the purge valve
While you crank. The engine will start.
Just another way to do it but somehow the starting procedure with mixture. cut off is more widely used .

[DanH]

Purge, then.....

Mixture rich, throttle position suitable for 900~1000 RPM, purge valve in bypass position.

Start cranking. Let a few blades go by, then slowly ease the purge valve closed.

[Geico266]

Originally Posted by DanH

Purge, then.....

Mixture rich, throttle position suitable for 900~1000 RPM, purge valve in bypass position.

Start cranking. Let a few blades go by, then slowly ease the purge valve closed.

Furl pump on or off?

[DanH]

Originally Posted by Geico266

Furl pump on or off?

Off, but it probably doesn't matter. Sounds like Ernst does the same procedure with the pump on.

[Geico266]

Originally Posted by DanH

Off, but it probably doesn't matter. Sounds like Ernst does the same procedure with the pump on.

And I think that makes sense.

[David-aviator]

Originally Posted by N427EF

Another successful method to hot start is using the purge valve in the following manner:
Purge the system as you have described but now leave the boost pump
On, Set throttle, mixture rich, start cranking and close the purge valve
While you crank. The engine will start.
Just another way to do it but somehow the starting procedure with mixture. cut off is more widely used .

My deal with purge valve is about the same and simple. First thing while strapping and getting ATIS, turn boost pump on and let it circulate fuel. When ready to start, hit the starter and push the purge valve in at the same time (fuel to divider). Engine goes VAROOM.

When the engine was cold, it gets 3-4 seconds of prime (purge valve in) after circulate, hit the starter and purge valve in at the same time. It works quite well.

Boost pump stays on until after take off except for a check to make sure the engine pump was working. Always shut down with purge valve. I like it, it's a much cleaner, quicker shut down than pulling the mixture.

[ExtraKatana]

5-5. The following instructions are recommended procedures for operating engines with engine driven fuel pumps.

COLD STARTS
* Purge valve off (?ICO? position).
* Mixture control "FULL RICH".
* Throttle open ? or more.
* Turn on boost pump. Run for 30-45 seconds
* Put purge valve to run (?R? position), count to five then return purge valve to off position. Actual prime time may be different from installation to installation. If the engine tends to flood, reduce the throttle to off idle then prime the engine.
* Reduce throttle to 1/8 or off idle.
* Leave the Mixture control in the full rich position.
* With mags "HOT?, crank engine, when engine fires, put the purge valve in the run position and the throttle to idle. After the engine stablizes idle, the boost pump can be shut off.

ENGINE SHUT DOWN
* Bring engine to idle speed.
* Leave mixture control "FULL RICH".
* Turn boost pump off.
* Put purge valve control to "OFF" position.
* Turn off the ignition.

HOT STARTS
* Mixture control "FULL RICH".
* Throttle ? to wide open.
* Purge valve "OFF" position.
* Turn on boost pump and let run 30 to 45 seconds. This will purge the hot fuel and vapor from the system, and will cool and fill the fuel system components with cool fuel.
* Leave the boost pump on.
* Set Throttle to 1/8 open.
* Give engine a short prime by putting the purge valve to ?run? then back to ?off?. The amount of prime required my vary from installation to installation.
* Leave Mixture control "Full Rich?.
* With mags "HOT?, crank engine, when engine fires, return throttle to idle and purge valve to ?Run".
* Leave the boost pump on during hot, low power, operation.

Another method for starting the engine when hot is to leave the mixture ?rich? after purging the system. With the purge valve in the ICO position and the throttle at idle, crank the engine while slowly moving the purge valve to the Rich position. The engine will start during this movement to the Rich position.

[PIN 37]

HOT STARTS
* Mixture control "FULL RICH".
* Throttle ½ to wide open.
* Purge valve "OFF" position.
* Turn on boost pump and let run 30 to 45 seconds. This will purge the hot fuel and vapor from the system, and will cool and fill the fuel system components with cool fuel.
* Leave the boost pump on.
* Set Throttle to 1/8 open.
* Give engine a short prime by putting the purge valve to “run” then back to “off”. The amount of prime required my vary from installation to installation.
* Leave Mixture control "Full Rich”.
* With mags "HOT”, crank engine, when engine fires, return throttle to idle and purge valve to “Run".
* Leave the boost pump on during hot, low power, operation.

That is exactly the procedure used on our company RV6 except the bit about using the purge valve (bolded). The 360 engine has Airflow Performance fuel injection, but has had the purge valve removed. I have similar on my RV7 and have also removed the purge valve. We dont have any problems with hot starts and it it can get very hot here. For instance its 44C here today