Today's Message Index:
----------------------
1. 01:06 PM - Re: Low fuel pressure injected engine (Michele Delsol)
2. 02:51 PM - Re: Low fuel pressure indication (Charlie England)
3. 06:19 PM - Re: Low fuel pressure injected engine (Robin Marks)
Message 1
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Subject: | Low fuel pressure injected engine |
Not exactly ' should be around 155 at 2500=92 ' should have 160+
22/2400 at
6500=92 ' 8 US gal/hr. I have forward induction with the snorkel. A
James cowl
with direct forward air feed should get me some more MP and less air
intake
hence more power at altitude and less drag, but that is just
conjecturing.
And another thread.
On the fuel pressure issue ' two flights today ' problem did not
manifest
itself ' a mystery. Outside air temp around 60=B0F. Flew between
400=92 and
7500=92.
Mich=E8le
De : owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] De la part de Robin Marks
Envoy=E9 : samedi 29 juin 2013 07:26
=C0 : rv-list@matronics.com
Objet : RE: RV-List: Low fuel pressure injected engine
Mich=E8le
Do you know your TAS at those settings?
Robin
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Michele Delsol
Sent: Friday, June 28, 2013 11:57 AM
Subject: RV-List: Low fuel pressure injected engine
Hello to all,
While the subject is on fuel pressure (carbureted engine) I thought
I=92d
relate a little problem I am encountering on occasion in my fuel
injected
engine.
I=92d be putting along at cruise speed when all of a sudden, some slight
misfire, loss of poser. I look at the fuel pressure and it is down from
26
psi to the low teens. A slight touch of the boost pump and the problem
disappears. Turn the boost pump off and the pressure continues up there
at
27 psi and I can continue and hour or more ' no incident.
Set up : TMX-360 (AKA IO-360), Precision Airmotive Silver Hawk Fuel
injection, standard injectors. Pmag and Slick. I run at 24/2400 8 USG/hr
and
get 150 knts ias.
Temporary vapor lock ? Mechanical fuel pump is beginning to have
problems ?
It=92s a glitch ' it does not happen on all flights and does not seem
related
to outside air temp. Any ideas ???
This does not keep me from flying but since the boost pump has become a
life
line, I am installing Andair=92s new fuel pump in line with the boost
pump as
a back up boost pump in case things get a little nasty.
Regards,
Mich=E8le
RV8 ' TMX-360
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Message 2
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Subject: | Re: Low fuel pressure indication |
There have been numerous threads on various lists & forums about low
fuel pressure indications with carb'd engines. Most indicate a sensor
design flaw, rather than an actual pressure issue. Here's a pretty good
example from VAF:
<http://www.vansairforce.com/community/showthread.php?t=97911&highlight=low+fuel+pressure>http://www.vansairforce.com/community/showthread.php?t=90682&highlight=low+fuel+pressure
Mike,
I'm not following how manifold pressure would affect a fuel pressure
reading, since with a carb'd engine the fuel pressure sensor is
measuring pressure between the engine pump & the inlet to the carb bowl
& isn't typically in the intake path. What am I missing?
Charlie
On 06/28/2013 12:10 PM, HCRV6@comcast.net wrote:
> Thanks Mike, excellent point that was escaping me.
>
> Harry
>
> ------------------------------------------------------------------------
> *From: *"Mike Robertson" <mrobert569@hotmail.com>
> *To: *"rv list" <rv-list@matronics.com>
> *Sent: *Thursday, June 27, 2013 11:25:15 AM
> *Subject: *RE: RV-List: Low fuel pressure indication
>
> Harry,
>
> Keep in mind that when we measure pressure we are really talking
> pressure differential. If the throttle is full open then the fuel
> pressure differential may actually be zero. For carb equipped
> airplanes I would not get too carried away with a zero reading at full
> throttle as long as the engine is running good and you still see some
> pressure when you turn on the boost pump.
>
> Mike Robertson
>
> ------------------------------------------------------------------------
> Date: Thu, 27 Jun 2013 18:07:25 +0000
> From: HCRV6@comcast.net
> To: RV-list@matronics.com
> Subject: RV-List: Low fuel pressure indication
>
> I have a puzzling problem and wondering if anyone can shed some light
> on it. Under continuous high power settings, like in climb to
> altitude after takeoff, my Grand Rapids EFIS fuel pressure indication
> drops to zero and even shows a low negative value after a couple of
> minutes, but the engine continues to run at full power. This with a
> carbureted O-360 and running on the engine driven pump only. If I
> switch the aux pump back on the pressure indication comes back to the
> normal 2 to 4 psi range. I had this problem a few years ago and
> installing a new VDO pressure sender from Grand Rapids cured it, but
> this time a new sender did not help. The pressure take off is at the
> carburetor and the sender is mounted on the firewall, connected with a
> -2 hose.
>
> The thing that has me scratching my head is that the engine keeps
> running fine at high fuel flow even though the fuel pressure indicates
> zero or less, so I would suspect a bum sender again, but the fact that
> the pressure indication comes back to normal when I turn the aux pump
> back on has me baffled.
>
> HarryCrosby
> RV-6 N16CX, 1080 hours
>
Message 3
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Subject: | Low fuel pressure injected engine |
I have the exact same thing happen to me (IO-360 200 Hp, James Cowl, Bendex
, Mag/Pmag)
I fly 21.5/2250 LOP at 6.2-6.8 GPH ~158 TAS. My cylinder & oil temps are qu
ite low because there is so little pressure & minimal internal stress vs. 2
4 or 25 Squared ROP. It sort of feels like my system is gently falling asle
ep and then the fuel pump takes a nap. Sometimes I hit the boost pump and s
ometimes I let it drop and then catch back up with rarely a stumble. I do o
ccasionally have a stumble but I thing that is more related to my most lean
cylinder (LOP) getting too lean vs. system fuel starvation.
Good luck,
Robin
From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matro
nics.com] On Behalf Of Michele Delsol
Sent: Saturday, June 29, 2013 1:07 PM
Subject: RE: RV-List: Low fuel pressure injected engine
Not exactly - should be around 155 at 2500' - should have 160+ 22/2400 at 6
500' - 8 US gal/hr. I have forward induction with the snorkel. A James cowl
with direct forward air feed should get me some more MP and less air intak
e hence more power at altitude and less drag, but that is just conjecturing
. And another thread.
On the fuel pressure issue - two flights today - problem did not manifest i
tself - a mystery. Outside air temp around 60=B0F. Flew between 400' and 75
00'.
Mich=E8le
De : owner-rv-list-server@matronics.com<mailto:owner-rv-list-server@matroni
cs.com> [mailto:owner-rv-list-server@matronics.com] De la part de Robin Mar
ks
Envoy=E9 : samedi 29 juin 2013 07:26
=C0 : rv-list@matronics.com<mailto:rv-list@matronics.com>
Objet : RE: RV-List: Low fuel pressure injected engine
Mich=E8le
Do you know your TAS at those settings?
Robin
From: owner-rv-list-server@matronics.com<mailto:owner-rv-list-server@matron
ics.com> [mailto:owner-rv-list-server@matronics.com] On Behalf Of Michele D
elsol
Sent: Friday, June 28, 2013 11:57 AM
Subject: RV-List: Low fuel pressure injected engine
Hello to all,
While the subject is on fuel pressure (carbureted engine) I thought I'd rel
ate a little problem I am encountering on occasion in my fuel injected engi
ne.
I'd be putting along at cruise speed when all of a sudden, some slight misf
ire, loss of poser. I look at the fuel pressure and it is down from 26 psi
to the low teens. A slight touch of the boost pump and the problem disappea
rs. Turn the boost pump off and the pressure continues up there at 27 psi a
nd I can continue and hour or more - no incident.
Set up : TMX-360 (AKA IO-360), Precision Airmotive Silver Hawk Fuel inject
ion, standard injectors. Pmag and Slick. I run at 24/2400 8 USG/hr and get
150 knts ias.
Temporary vapor lock ? Mechanical fuel pump is beginning to have problems ?
It's a glitch - it does not happen on all flights and does not seem relate
d to outside air temp. Any ideas ???
This does not keep me from flying but since the boost pump has become a lif
e line, I am installing Andair's new fuel pump in line with the boost pump
as a back up boost pump in case things get a little nasty.
Regards,
Mich=E8le
RV8 - TMX-360
===================
bsp; - The RV-List Email Forum -
o browse
scription,
, Chat, FAQ,
/span>
tronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List
===================
bsp; - MATRONICS WEB FORUMS -
eb Forums!
.matronics.com">http://forums.matronics.com
===================
bsp; - List Contribution Web Site -
o:p>
bsp; -Matt Dralle, List Admin.
tronics.com/contribution">http://www.matronics.com/contribution
===================
________________________________
No virus found in this message.
Checked by AVG - www.avg.com<http://www.avg.com>
:p>
http://www.matronics.com/Navigator?RV-List
http://forums.matronics.com
http://www.matronics.com/contribution
________________________________
No virus found in this message.
Checked by AVG - www.avg.com<http://www.avg.com>
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