Today's Message Index:
----------------------
1. 07:41 AM - Re: Fuel pump tests (Hinde, Frank George (Corvallis))
2. 07:51 AM - Re: Fuel pump tests (BELTEDAIR@aol.com)
3. 08:16 AM - Re: Fuel pump tests (Hinde, Frank George (Corvallis))
4. 02:06 PM - Re: Fuel pump tests (n801bh@netzero.com)
5. 05:33 PM - Fuel pump tests (Gene Smith)
Message 1
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But didn't you say you saw bubbles with the clear hoses? This implies the onset
of fuel boiling on the suction side of the pump. I guess my concern is if you
saw bubbles on the ground then these bubbles are likely to be larger at the conditions
I described. In other words my concern is you might be getting a little
close to a true vapour lock situation.
Cheers
Frank
-----Original Message-----
From: owner-engines-list-server@matronics.com [mailto:owner-engines-list-server@matronics.com] On Behalf Of Gilles Thesee
Sent: Thursday, March 15, 2007 1:17 PM
Subject: Re: Engines-List: Fuel pump tests
--> <Gilles.Thesee@ac-grenoble.fr>
Hinde, Frank George (Corvallis) a crit :
> --> <frank.hinde@hp.com>
>
>
> Your right that is exactly what is happening. It also gets worse as
> the temperature of the fuel increases, namely thru a hot engine driven
> pump...I gets worse further with altitude and the harder you suck on
> the fuel. When it gets really bad its called vapour lock and your
> engine quits. It will also happen more with autofuel than with 100LL
> due to the higher vapour pressure of the mogas. Low wing airplanes
> (with wing tanks and no header tank are much more susceptable because
> the engine driven pump is sucking uphill.
>
> This coindiently may happen at the worse possible time i.e a hot
> Summer day at a high altitude airport where your fuel has been heat
> soaked....You run full power, the engine gets real hot and Here come
> the trees!
>
> So, what to do?....Mount a low pressure electric pump as close to the
> outlet of tha tank as possible with no pressure drop on the inlet side
> of the pump.
>
Frank,
Thank you for responding.
Actually we have wing tanks and our pumps are on the firewall, some inches higher
than wing root level. To date we've reached FL 145 in winter on Avgas, and
recently flew at FL 135 on Mogas without any problems.
I also flew at 37C OAT (only up to 6000 ft).
But you're right on the pumps in the wing roots in a perfect circuit.
Best regards,
Gilles
http://contrails.free.fr
Message 2
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Subject: | Re: Fuel pump tests |
Dear List:
I have just gotten in on the tail end of this problem, but we have been
working with people to come to a solution. We found the fuel selector valve on
low
wing planes to be leaking air around the shaft but not leaking fuel. IF it
were a high wing with a lot of head pressure fuel would seep out. But on low wing
planes fuel does not seep out but air in. We built a manometer to prove the
theory. We changed the .06 cent "O"ring around the shaft then put a drop of
engine oil to make sure it did not pull in. We experienced engine roughness at
high power settings returning to normal at lower power settings. If the aux fuel
pump were turned on, it made the condition worse. In early 2006 we went back
5 years in the NTSB files and found 99 instances where the engine quit then
would run when it was removed from the wreckage. Fuel injected engines are worse
due to the high suction. It equates to putting a hole in a straw and trying
to drink. This was found on the "Imperial" type valve. This valve was and is
used in most GA and experimetal craft.
Jess
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Message 3
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Excuse my sceptisism but it seems you are now relying on a 25cent O
ring... and a single point of failure to boot.
Personally i would rather redesign the system to be "hydraulically
correct" i.e no sucking anywhere in the system as a fuel leak is a minor
problem that has good warning qualities (stink). And air leak has almost
no warning qualities until your engine stumbles or quits.
Of course if you have big lines and very low pressure drop through the
valve on the inlet side to the pump the problem is much reduced on a
suck type system, but if you have electric pumps anyway then its worth
putting them in the correct place if space permits.
As you say, this has resulted in wreckage!
Frank
________________________________
From: owner-engines-list-server@matronics.com
[mailto:owner-engines-list-server@matronics.com] On Behalf Of
BELTEDAIR@aol.com
Sent: Friday, March 16, 2007 7:51 AM
Subject: Re: Engines-List: Fuel pump tests
Dear List:
I have just gotten in on the tail end of this problem, but we have been
working with people to come to a solution. We found the fuel selector
valve on low wing planes to be leaking air around the shaft but not
leaking fuel. IF it were a high wing with a lot of head pressure fuel
would seep out. But on low wing planes fuel does not seep out but air
in. We built a manometer to prove the theory. We changed the .06 cent
"O"ring around the shaft then put a drop of engine oil to make sure it
did not pull in. We experienced engine roughness at high power settings
returning to normal at lower power settings. If the aux fuel pump were
turned on, it made the condition worse. In early 2006 we went back 5
years in the NTSB files and found 99 instances where the engine quit
then would run when it was removed from the wreckage. Fuel injected
engines are worse due to the high suction. It equates to putting a hole
in a straw and trying to drink. This was found on the "Imperial" type
valve. This valve was and is used in most GA and experimetal craft.
Jess
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Message 4
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Subject: | Re: Fuel pump tests |
Jess makes a good redrive unit and lives where is is" hot" in the summer
, in fact it is in the 90's down there now. YUCK. Jess,I am assuming yo
u are running mogas in your V-6 Chevy.If so have you ever had a vapor lo
ck condition in the extreme heat of Las Vegas? I made a test of mogas o
n my beast last year and it hiccuped at 13,000 and 45f degrees. That go
t my attention but I safely made it back on the ground.I am not sure the
fuel was the problem though because I made some other changes at the sa
me time trying to get the oil cooler to shed more heat and probably elev
ated the under cowl temp too much which heated up the fuel lines going t
o the carb. Plane goes up to 17,999 msl perfectly on 100LL. I would like
to hear stories from people on past experiences of runnig mogasand vapo
r lock issues.
thanks in advance.
do not archive
Ben Haas
N801BH
www.haaspowerair.com
-- BELTEDAIR@aol.com wrote:
Dear List:I have just gotten in on the tail end of this problem, but we
have been working with people to come to a solution. We found the fuel s
elector valve on low wing planes to be leaking air around the shaft but
not leaking fuel. IF it were a high wing with a lot of head pressure fue
l would seep out. But on low wing planes fuel does not seep out but air
in. We built a manometer to prove the theory. We changed the .06 cent "O
"ring around the shaft then put a drop of engine oil to make sure it did
not pull in. We experienced engine roughness at high power settings ret
urning to normal at lower power settings. If the aux fuel pump were turn
ed on, it made the condition worse. In early 2006 we went back 5 years i
n the NTSB files and found 99 instances where the engine quit then would
run when it was removed from the wreckage. Fuel injected engines are wo
rse due to the high suction. It equates to putting a hole in a straw and
trying to drink. This was found on the "Imperial" type valve. This valv
e was and is used in most GA and experimetal craft.Jess
AOL now offers free email to everyone. Find out more about what's free f
========================
========================
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======
<html><P>Jess makes a good redrive unit and lives where is is" hot" in t
he summer, in fact it is in the 90's down there now. YUCK. Jess,I
am assuming you are running mogas in your V-6 Chevy.If so have you
ever had a vapor lock condition in the extreme heat of Las Vegas?
I made a test of mogas on my beast last year and it hiccuped at 13,000 a
nd 45f degrees. That got my attention but I safely made it back on
the ground.I am not sure the fuel was the problem though because I
made some other changes at the same time trying to get the oil cooler t
o shed more heat and probably elevated the under cowl temp too much whic
h heated up the fuel lines going to the carb. Plane goes up to 17,999 ms
l perfectly on 100LL. I would like to hear stories from people on past e
xperiences of runnig mogasand vapor lock issues.</P>
<P>thanks in advance.</P>
<P>do not archive<BR><BR><BR>Ben Haas<BR>N801BH<BR>www.haaspowerair
.com<BR><BR>-- BELTEDAIR@aol.com wrote:<BR></P>
<DIV><FONT color=#0000ff size=4>Dear List:</FONT></DIV>
<DIV><FONT color=#0000ff size=4>I have just gotten in on the tail en
d of this problem, but we have been working with people to come to a sol
ution. We found the fuel selector valve on low wing planes to be leaking
air around the shaft but not leaking fuel. IF it were a high wing with
a lot of head pressure fuel would seep out. But on low wing planes fuel
does not seep out but air in. We built a manometer to prove the theory.
We changed the .06 cent "O"ring around the shaft then put a drop of engi
ne oil to make sure it did not pull in. We experienced engine roughness
at high power settings returning to normal at lower power settings. If t
he aux fuel pump were turned on, it made the condition worse. In early 2
006 we went back 5 years in the NTSB files and found 99 instances where
the engine quit then would run when it was removed from the wreckage. Fu
el injected engines are worse due to the high suction. It equates to put
ting a hole in a straw and trying to drink. This was found on the "Imper
ial" type valve. This valve was and is used in most GA and experimetal c
raft.</FONT></DIV>
<DIV><FONT color=#0000ff size=4>Jess</FONT></DIV><BR><BR><BR>
<DIV><FONT style="FONT: 10pt ARIAL, SAN-SERIF; COLOR: black">
<HR style="MARGIN-TOP: 10px">
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rom AOL at <A title=http://www.aol.com?ncid=AOLAOF00020000000339 hre
f="http://www.aol.com/?ncid=AOLAOF00020000000339" target=_blank><B
>AOL.com</B></A>. </FONT></DIV><PRE><B><FONT face="courier new,courier
" color=#000000 size=2>
========================
===========
t">http://www.matronics.com/Navigator?Engines-List</A>
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===========
tronics.com</A>
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===========
</B></FONT></PRE>
<pre><b><font size=2 color="#000000" face="courier new,courier">
</b></font></pre></body></html>
Message 5
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OK, I hate to mention this because I haven't tried it myself...I used to
use mogas in my RV-4(Lyc. 0320/160) and lots of folks at OSH do the
same, now I only use 100LL in the summer, S. Tx is just too hot, plus
the additives in mogas scare me, and as you know some companies are
using 10% ethanol, and don't count on the pump to be marked as such.
In a discussion about vapor-lock and etc., this one builder showed me
what he did to prevent V/L...He sprayed the fuel pump(mechanical), fuel
lines, and gascolator with a thick coating of SPRAY INSULATION FOAM all
the way to the fire-wall...He did a neat job of applying the goop...I
assume he used some form of shielding while spraying because there was
no overspray anywhere else...I don't know if he sprayed the boost pump
or not, he didn't mention it or show it to me...I asked about working on
the units, and he said no problem, you use a knife and cut the foam away
so you can get a wrench on the nuts and bolts or a screwdriver on the
screws...When you get through, you simply squirt it some more with foam.
Some of you experts out there must have an opinion on this or maybe some
sort of experience in this area.
I don't advocate this for anyone out there, and I repeat, I have never
used this foam or a insulated wrap........Good
Luck........................CHEERS!!!!................................Gen
e Smith, 1994 RV-4.
----- Original Message -----
From: n801bh@netzero.com
To: engines-list@matronics.com
Sent: Friday, March 16, 2007 3:05 PM
Subject: Re: Engines-List: Fuel pump tests
Jess makes a good redrive unit and lives where is is" hot" in the
summer, in fact it is in the 90's down there now. YUCK. Jess,I am
assuming you are running mogas in your V-6 Chevy.If so have you ever had
a vapor lock condition in the extreme heat of Las Vegas? I made a test
of mogas on my beast last year and it hiccuped at 13,000 and 45f
degrees. That got my attention but I safely made it back on the
ground.I am not sure the fuel was the problem though because I made some
other changes at the same time trying to get the oil cooler to shed more
heat and probably elevated the under cowl temp too much which heated up
the fuel lines going to the carb. Plane goes up to 17,999 msl perfectly
on 100LL. I would like to hear stories from people on past experiences
of runnig mogasand vapor lock issues.
thanks in advance.
do not archive
Ben Haas
N801BH
www.haaspowerair.com
-- BELTEDAIR@aol.com wrote:
Dear List:
I have just gotten in on the tail end of this problem, but we have
been working with people to come to a solution. We found the fuel
selector valve on low wing planes to be leaking air around the shaft but
not leaking fuel. IF it were a high wing with a lot of head pressure
fuel would seep out. But on low wing planes fuel does not seep out but
air in. We built a manometer to prove the theory. We changed the .06
cent "O"ring around the shaft then put a drop of engine oil to make sure
it did not pull in. We experienced engine roughness at high power
settings returning to normal at lower power settings. If the aux fuel
pump were turned on, it made the condition worse. In early 2006 we went
back 5 years in the NTSB files and found 99 instances where the engine
quit then would run when it was removed from the wreckage. Fuel injected
engines are worse due to the high suction. It equates to putting a hole
in a straw and trying to drink. This was found on the "Imperial" type
valve. This valve was and is used in most GA and experimetal craft.
Jess
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