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Hi, Kelly....I wish I had only made and tested one
modification at a time. I don't know for sure if it was bypassing of the
Facet pump or installing the vent in the sump tank that made the
difference. I may reconnect the Facet pump and try one more time to see if
I can induce vapor lock. My thinking is that I should have seen bubbles in
the clear fuel line that I used to bypass the Facet, trying to work their way
back to the main tanks. I could see nothing, unless they were so miniscule that
the naked eye could not see them. We did, however see movement of air/bubbles
from the top of the sump tank going into the main fuel tank. Most of the
time, the small amount of fuel in the newly installed sump tank vent line just
stayed about halfway between the sump tank and the main tank. Under higher power
loading, the fuel/bubbles would start drifting uphill toward the main fuel tank.
Prior to installing the vent and
bypassing the Facet pump, I could easily and repeatedly induce vapor lock.
If I either plug the sump or reconnect the Facet, one of those should let me
induce vapor lock again. At least that's the assumption I am making, (and
we all know about making assumptions). I think that un-doing these mods
one at a time would be the most scientific method of finding out which one was
actually the cure. If you take both Excedrin and Aspirin for a headache,
it's difficult to know which one cured the headache. Paul Conner
----- Original Message -----
Sent: Monday, February 21, 2005 7:30
PM
Subject: [FlyRotary] Re: No more vapor
lock
Paul,
Does this mean the Facet fuel pump is history ??
--
Kelly Troyer
Dyke
Delta/13B/RD1C/EC2
--------------
Original message from "Paul" <sqpilot@bellsouth.net>:
--------------
Well, after several mods to my airplane, which
include installing firesleeve on all fuel lines, installing a vent for the
sump tank (into the main wing tank) and bypassing the Facet fuel pump with a
short length of clear tubing, I ran the engine until the water temp hit 230
degrees. I shut it down and let the heat soaking proceed. Then I
restarted the engine and ran it up to 240 degrees. Still was able to go to
full power with no signs of the engine stumbling or running rough.
Finally, temps hit 250 and I could hear the surge tank spitting out steam
and liquid, but WOT was still smooth. Previously it would stumble and
quit by the time I hit 230. I taxiied back in and temps only came down
to around 220, so we placed the fan under the NACA scoop to cool it
down. There was evidence of small bubbles coming out of the top of the
aluminum sump tank (which remained cool to the touch even at 250 degrees
water temp), going into the left fuel strake. Itwas a small amount, but
nevertheless, it was evident that the vent was working. There was no
evidence of any bubbles coming out of the bottom of the surge tank and
trying to work their way back up towards the fuel selector valve (through
the line that the Facet pump normally resides). I ran it again today,
but just to normal 180 degree temps, and it still ran fine. Paul
Conner
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