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  #11  
Old 03-17-2014, 04:42 PM
gereed75 gereed75 is offline
 
Join Date: Sep 2007
Location: pittsburgh pa
Posts: 533
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Thanks Bob. Always wondered about the gurgling sound!!
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  #12  
Old 03-17-2014, 09:25 PM
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AlexPeterson AlexPeterson is offline
 
Join Date: Sep 2005
Location: Maple Grove, MN
Posts: 2,333
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I've seen this forever in mine. As the weather gets colder, one will need more prime prior to cranking if you want it to fire off after a couple blades. At idle, so little air is flowing up the induction tubes that it will not pull the extra fuel up hill. Additionally, as someone else posted, the fuel in the flow distributor and lines dumps into the engine once it is shutdown. If you are not running a purge valve, there will be additional fuel which might boil up from the servo and connecting hose.

I drilled a hole in the bottom of the FAB, inside the aft end of the filter, to allow the goo to drain. I glued a fitting on the bottom side of this hole, onto which I have a hose attached to dump the stuff behind the cowl aft end.

5 seconds with the throttle at idle will not be enough to start my engine without a fair bit of cranking, btw (AFP system).
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RV6A N66AP 1700+ hours
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  #13  
Old 03-17-2014, 09:45 PM
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IowaRV9Dreamer IowaRV9Dreamer is offline
 
Join Date: Jan 2005
Location: Marion IA
Posts: 1,095
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I'm flying behind a 200 HP angle valve IO-360 with Bendix FI.

If I ever opened the throttle and mixture full, and ran the pump for 5 full seconds, my engine would be totally flooded with fuel pouring out the sniffle valve.

For cold start (starts on 2nd blade usually):
mixture full rich
throttle cracked 1/4 inch or so
boost pump on for 2-3 seconds then off
start

For hot start (starts after 3-4 seconds of cranking):
mixture idle cusoff
throttle cracked 1/4 inch or so
start
open mixture as engine catches.

I imagine the smaller FI engines are similar.
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Dave Gribble VAF #232
Building RV-9A N149DG (slider, IO-320, IFR)
Restored and Flying Beech Super III N3698Q
Marion IA

Struggling with fiberglass

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  #14  
Old 03-17-2014, 10:11 PM
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skylor skylor is offline
 
Join Date: Aug 2009
Location: Southern California
Posts: 882
Default Priming



200 Hp IO-360 Angle Valve:

What works for me for a cold start is:

Full Throttle
Full Mixture
2-3 seconds boost pump (warm weather); 3-4 seconds boost pump (cool weather*)
Pump Off
Mixture-ICO
Throttle-Slightly cracked open
Hit the starter & advance the mixture as it catches. Fires on 1-2 blades every time (with mags)

*Cool weather by SoCal standards = 50-60 degrees.

Skylor
RV-8
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  #15  
Old 03-17-2014, 10:22 PM
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RVG8tor RVG8tor is offline
 
Join Date: Mar 2007
Location: McKinney, TX
Posts: 1,261
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Quote:
Originally Posted by AlexPeterson View Post
I've seen this forever in mine. As the weather gets colder, one will need more prime prior to cranking if you want it to fire off after a couple blades. At idle, so little air is flowing up the induction tubes that it will not pull the extra fuel up hill. Additionally, as someone else posted, the fuel in the flow distributor and lines dumps into the engine once it is shutdown. If you are not running a purge valve, there will be additional fuel which might boil up from the servo and connecting hose.

I drilled a hole in the bottom of the FAB, inside the aft end of the filter, to allow the goo to drain. I glued a fitting on the bottom side of this hole, onto which I have a hose attached to dump the stuff behind the cowl aft end.

5 seconds with the throttle at idle will not be enough to start my engine without a fair bit of cranking, btw (AFP system).
I am with you Alex, AFP fuel injection. I tried using less than 5 sec prime on a cold engine and it takes a lot longer to start.

I have a drain hole on the low spot on the FAB, I never thought to run a drain hose.
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N800ME
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  #16  
Old 03-18-2014, 06:44 AM
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Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,686
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Quote:
Originally Posted by RVG8tor View Post
I am with you Alex, AFP fuel injection. I tried using less than 5 sec prime on a cold engine and it takes a lot longer to start.
That's because FF with no airflow thru the servo is practically 0 with the throttle closed, full throttle allows the fuel to flow at about a 4GPH rate. About 1-2 secs with full throttle works perfect for me.
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EXP Aircraft Services LLC
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  #17  
Old 03-18-2014, 08:39 AM
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jdeas jdeas is offline
 
Join Date: Mar 2006
Location: SoCal
Posts: 626
Default Fuel in FAB

Quote:
Originally Posted by RV10inOz View Post
What Bob said....and do not over prime, 5 seconds is far too long no matter who said it in their manuals
I am using 3 seconds pump on start. The engine still starts after a few blades.
Fuel stains still in the FAB. On occasion I have flooded on hot starts causing fuel in the FAB to leak down through the FAB's aux air onto the bottom cowl.
Not a good thing as the fuel does a great job dissolving the glue holding my heat shield (foil) on the cowl
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----------------------
RV-7 N314SY (KWHP)
IO-360-B1B

CANbus based trim/flaps and electrical
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  #18  
Old 03-18-2014, 10:23 AM
RVDan RVDan is offline
 
Join Date: Jun 2012
Location: Frederick, MD
Posts: 821
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The mixture control can also be leaky so that when you go to full lean, it still lets a bit of fuel by. If there is residual fuel pressure or if you have the electric pump on after shutdown, fuel can leak by the mixture valve and continue to flow out of the nozzles. The Bendix RSA series had AD's on them for leakage at the mixture valve. The Airfolw Performance servos use a different valve arrangement and do often leak by also. I an AFP one a while back which was leaky, which at that time AFP had said was normal.
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Frederick, MD
PA28-140
Hph 304CZ
RV6 built and sold
N199EC RV6A flying
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  #19  
Old 03-18-2014, 04:37 PM
Paul K Paul K is offline
 
Join Date: Mar 2009
Location: Grand Rapids, MI
Posts: 1,004
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In in the 2 to 3 second prime group and have not had any issues with starting. I also have fuel drain out of the cowl down the front gear fairing onto the front wheel pant! Done it forever and can't find any source other than back out the servo and out my snorkel drain hole after shutdown.
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West Michigan

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  #20  
Old 03-18-2014, 09:27 PM
hudgin hudgin is offline
 
Join Date: Apr 2007
Location: Cedar Hill, Tx.
Posts: 159
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Sometimes the servo is just plain broken. To test it plug the fuel line at the flow divider and open the mixture and throttle full. Turn on the fuel pump and while it is running check that no fuel is coming out of the impact tubes. If there is send it to your favorite fuel system fixen place. That is something that should be done every year.
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