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  #1  
Old 03-17-2014, 10:12 AM
LettersFromFlyoverCountry's Avatar
LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Location: St. Paul, MN.
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Default Fuel in the FAB

Here's the looks of things when I took off the FAB for the conditional, on an IO-360-M1B.





What can cause accumulation of 100L?
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  #2  
Old 03-17-2014, 10:45 AM
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tadsargent tadsargent is offline
 
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I hope he is not pumping the throttle while starting an injected engine. If you are, don't

I think you have a leak in your servo. I would pressurize the system with the throttle closed and the mixture in the rich position. Examine the throttle and mixture barrels, these O rings may need changing.
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  #3  
Old 03-17-2014, 10:57 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Starting technique is as Mattituck said:

Throttle full open
Mixture full open
Boost pump 5 seconds
Throttle full closed
Mixture to cutoff
Boost pump off
Throttle 1/8
Engage starter
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St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
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  #4  
Old 03-17-2014, 11:12 AM
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RVG8tor RVG8tor is offline
 
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Default Same thing

I posted a thread a few weeks ago. I tend to get the same thing, it looks like some oil mixing in with the fuel, make a thick blueish film. No one seemed to have any ideas or noted that this was normal. I am continuing to fly since things are working normally and I can't find what the deal might be.

I was told I might be over priming, I was using 5 sec per the Air Flow Performance (AFP) instructions, for a cold start, none or 2 sec for a hot start.

I look forward to what others reply here. This is a shot of mine right after the FAB came off. Mine has a heavier build up than yours. I can see where one might over prime but why would it not get sucked back up into the engine.



Maybe Don from AFB will see this and shed some light, could be fuel settling after shutdown.

Cheers
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  #5  
Old 03-17-2014, 11:22 AM
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tadsargent tadsargent is offline
 
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Starting technique is as Mattituck said:

Throttle full closed
Mixture full open
Boost pump 5 seconds
Throttle full closed
Mixture to cutoff
Boost pump off
Throttle 1/8
Engage starter

My changes to your technique in red

This is my hot start technique

The cold start process leaves the mixture in full rich, all else is the same. In either case the throttle is only opened just prior to starter engagement.
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Last edited by tadsargent : 03-17-2014 at 11:24 AM.
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  #6  
Old 03-17-2014, 11:48 AM
kbelue kbelue is offline
 
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Quote:
Originally Posted by LettersFromFlyoverCountry View Post
Starting technique is as Mattituck said:

Throttle full open
Mixture full open
Boost pump 5 seconds
Throttle full closed
Mixture to cutoff
Boost pump off
Throttle 1/8
Engage starter
I use this same procedure for cold starts with my IO-540 in my RV-10 and I find the same kind of residue in the FAB. It comes from fuel running back down the intake tubes during this start procedure. I'm going to try Tadsargent's method of keeping the throttle closed during fuel pump run. It seems like this method might take longer to start but I don't think it would cause fuel residue in the FAB.

Kevin Belue
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RV-10
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  #7  
Old 03-17-2014, 12:14 PM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Please let me know what you find out, Kevin. I'm apart for the condition and won't be able to try it for awhile.
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  #8  
Old 03-17-2014, 02:22 PM
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This is not unusual for a fuel injected engine. If the sniffle valves are not at the lowest points of the induction system you will get fuel in the airbox. With a vertical servo and stock sump there are no sniffle valves. As fuel boils out of the injector lines after shutdown small streams of fuel flow down the intake tubes and end up at the lowest points of the system. The gurgling sound you typically hear on a FI engine after shutdown is the fuel boiling out of the injector lines.

The stains build up over time making it appear like there is more leakage then there actually is.
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Last edited by rocketbob : 03-17-2014 at 02:26 PM.
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  #9  
Old 03-17-2014, 04:22 PM
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What Bob said....and do not over prime, 5 seconds is far too long no matter who said it in their manuals
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  #10  
Old 03-17-2014, 05:25 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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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
+1 what David said... on both counts....
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