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Date: Tue, 08 Feb 2005 11:45:30 -0600
From: Jim Sower <canarder@frontiernet.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Bad day at the airport
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Marc,
That's interesting.  I can't visualize how it wouldn't blow all the 
vapor through the fuel rail and injectors (they will pass a lot more air 
than fuel, even at lower pressure) but I have to accept that it 
happened.  How do you determine if a pump has a bleed circuit?  If not, 
or if you're not able to make the determination, would a small (1/8" OD 
line) downstream from the pump (perhaps at a high point in the fuel 
path) bypassing the regulator to the return line work? 

Inquiring minds need to know ... Jim S.

Mark R Steitle wrote:

>Paul,
>Do you have a bleed circuit between your pump and fuel pressure
>regulator? Do you have heat shields on your fuel lines? My guess is that
>you may have experienced vapor lock.  Without a bleed circuit, the fuel
>pump can't produce enough pressure to overcome the fuel pressure
>regulator.  I discovered this in my fuel system, as did some builders on
>the Eggenfelner group.  They actually had a couple of forced landings
>attributed to vapor lock.  I could reproduce this condition by letting
>my fuel pump suck air for a couple of seconds, then reinsert the pickup
>back into the tank.  This was to simulate running a tank dry, and then
>switching to the other tank.  With air in the lines, the pump couldn't
>overcome the back pressure from the regulator.  Only way to get it to
>run again was to crack the line to the injectors (with pump running)
>until the pump re-primed.  The bleed circuit allows this.  It has a
>.020" orifice, so it doesn't pass an excessive amount of fuel, but it
>will pass quite a bit of air.  Now, if I pull the pickup out of the tank
>and reinsert it, the pump will reprime in a few seconds.  In your case,
>I suspect that once you landed, there was enough time for engine/fuel
>system to cool enough to allow a restart.  Just a guess.  
>
>Mark S.  
>(Glad you weren't hurt, or the a/c either)    
>
>-----Original Message-----
>From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
>Behalf Of Ernest Christley
>Sent: Tuesday, February 08, 2005 8:16 AM
>To: Rotary motors in aircraft
>Subject: [FlyRotary] Re: Bad day at the airport
>
>Paul wrote:
>
>  
>
>>     
>>    Thanks, Bill....My next step is to pull the cowling and check
>>    plugs, filters, etc.  I will inspect the plugs to see what
>>    condition they are in. That can tell me a lot. I wish I hadn't
>>    re-started the engine to taxi back to the hangar. Running the
>>    engine after the problem might have covered up the problem, as it
>>    seemed to be running better on the taxi trip back to the hangar. 
>>    I'll report back with my findings.  Take care, and many thanks to
>>    everyone for their input and suggestions.  Paul, I'd rather be
>>    flying, Conner
>>     
>>
>>    
>>
>Paul, I got excited just reading your account.  Glad you and your plane 
>are still in one piece.
>
>Just to add to Bill's suggestion, the first car I owned was...let's say,
>
>'previously owned'.    Occasionaly, when you tried to get on the gas to 
>hard, it would die.  Always cranked right back up.  The problem went 
>away when I rebuilt the carb to clean out all the trash that would get 
>sucked up and block the jets (only when you really needed it not to).
>
>  
>
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>
>  
>
>>> Homepage:  http://www.flyrotary.com/
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>