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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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