Today's Message Index:
----------------------
1. 02:06 PM - Spiral Wrap (kearney)
2. 04:47 PM - Ongoing fuel pressure problems (Dan Charrois)
3. 06:08 PM - Re: Ongoing fuel pressure problems (John MacCallum)
4. 07:24 PM - Re: Ongoing fuel pressure problems (Kelly McMullen)
5. 10:33 PM - Re: Ongoing fuel pressure problems (Dan Charrois)
6. 10:44 PM - Re: Ongoing fuel pressure problems (Kelly McMullen)
7. 10:55 PM - Re: Ongoing fuel pressure problems (Bob Turner)
Message 1
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Hi
Does anyone have a source / spec for heat resistant spiral wrap. I'd like to use
some on the top of my engine so I don't want to use something that would melt.
Also, does anyone know how hot it get on top of the engine. I have found some
spiral wrap that is good to 160c but am unsure if that will survive -especially
after shut down.
Cheers
Les
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480898#480898
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| Subject: | Ongoing fuel pressure problems |
Hi everyone. I've had my RV-10 flying for about a year and a half now. Everything's
working fine except one issue - I periodically get low fuel pressure warnings
when just on the engine pump and haven't been able to isolate the problem.
My setup is pretty stock - a factory new Lycoming IO-540 D4A5 through Van's with
their pre-installed engine fuel pump, electric fuel pump assembly in the tunnel
as per Van's instructions, fuel plumbing as per Van's instructions, etc.
The only "deviation" from plans was that I had to install wing root gascolators
as per Canada's requirements.
My fuel totalizer is in the tunnel also as per instructions, though I realize now
that's a bad location in that it tends to over-read by 50% or more when the
electric boost pump is on. Not the end of the world since it's only an issue
when the electrical boost pump is on (which isn't really that much) and I'd rather
it read pessimistically instead of optimistically anyway. Maybe one day
I'll relocate it, but I mention it here in case someone thinks it's relevant
to my real problem.
And the real problem is this - normally in cruise above 10000', I have fuel pressure
readings around 19-21 psi. But periodically (and unpredictably) sometimes
the fuel pressure will plummet - I've seen it get as low as 10 psi before climbing
back up again. Originally, as soon as it would start dropping I'd turn
on the electric boost pump but as it's happened more and more often and I've
become more brave, I've held off at least a few seconds and so far it's always
recovered before the engine started stumbling.
I've never seen this happen with the boost pump on - just when the engine pump
is working on its own. Though as I said, I don't normally fly with the boost
pump on, so I obviously have less data with the boost pump on.
What's particularly interesting is that it only seems to happen at higher altitudes.
Above 10000' or so, I can count on it happening at least once an hour -
at 13000', it sometimes happens every 10 or 15 minutes (though sometimes it doesn't
happen at all either for an hour). At 9500', I've seen it happen only
rarely, and I don't recall it ever occurring at 8500' or below.
When it drops, it tends to fall over the course of about 5-10 seconds and then
climb back up over 5-10 seconds. The whole event is over with within 15-20 seconds,
and doesn't seem to "linger" at low PSI. I'm not sure if this is "real"
or an artifact of sensor filtering of the EFIS.
It isn't specific to when the engine is particularly hot - I always climb with
the boost pump on, so when the engine is running hotter I never see the issue.
This happens after I've been flying around at cruise power settings at altitude,
often with a below freezing outside temperature and CHTs in the 310-350 range,
and usually lean of peak burning in the neighbourhood of 10 gph.
I have a blast tube aimed towards the fuel pump (though not a full shroud). I've
even tried removing my gascolator screens in case they were potentially restricting
fuel flow.
It's been suggested that perhaps my fuel pressure sensor is having issues. I could
certainly change it out, but since I haven't seen an issue with the electric
boost pump on, and since it only seems to happen at altitude, I would expect
if it was a sensor issue neither of these two factors would have an effect.
Does anyone have any suggestions on what to try? I have tons of engine sensor
data logged from the EFIS that I could send if helpful.
I'm a bit apprehensive of changing out the fuel pump (in that I haven't done so
before and would want to ensure that a new one is installed correctly so I don't
damage anything). Has anyone done that before and could offer any advice?
On the other hand, I've lived with this one issue for long enough and as it's
the one thing I'm not completely happy with, I would like to try and finally
resolve it so I can better trust things.
Thanks for any advice!
Dan
---
Dan Charrois
President, Syzygy Research & Technology
Phone: 780-961-2213
Message 3
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| Subject: | Re: Ongoing fuel pressure problems |
Hi Dan,
=46rom a Video I watched about Fuel Injected engines as long as there is pos
itive pressure above about 5 PSI at high fuel flows to the FI Servo the engi
ne will run fine. The Video was from Tempest Aero parts and it talked about E
ngine driven Fuel Pumps and Boost Pumps. The Video was Titled, =9CThe
Amazing Ubiquitous Diaphragm Fuel Pump.=9D
Anyway the Video said nothing to worry about down to about 9 psi. What type o
f boost pump do you have? My Andair Electric boost pump is in the tunnel and
so is the red cube. I have no issues with inaccurate flow readings but I do
occasionally get fuel pressure fluctuations in very hot weather. That is am
bient ground temps above 35 C. I solve this by running the boost pump until a
t altitude and the OAT has dropped below 30 C.
Cheers John MacCallum
VH-DUU
> On 15 Jun 2018, at 09:45, Dan Charrois <dan@syz.com> wrote:
>
>
> Hi everyone. I've had my RV-10 flying for about a year and a half now. E
verything's working fine except one issue - I periodically get low fuel pres
sure warnings when just on the engine pump and haven't been able to isolate t
he problem.
>
> My setup is pretty stock - a factory new Lycoming IO-540 D4A5 through Van'
s with their pre-installed engine fuel pump, electric fuel pump assembly in t
he tunnel as per Van's instructions, fuel plumbing as per Van's instructions
, etc. The only "deviation" from plans was that I had to install wing root g
ascolators as per Canada's requirements.
>
> My fuel totalizer is in the tunnel also as per instructions, though I real
ize now that's a bad location in that it tends to over-read by 50% or more w
hen the electric boost pump is on. Not the end of the world since it's only
an issue when the electrical boost pump is on (which isn't really that much
) and I'd rather it read pessimistically instead of optimistically anyway. M
aybe one day I'll relocate it, but I mention it here in case someone thinks i
t's relevant to my real problem.
>
> And the real problem is this - normally in cruise above 10000', I have fue
l pressure readings around 19-21 psi. But periodically (and unpredictably) s
ometimes the fuel pressure will plummet - I've seen it get as low as 10 psi b
efore climbing back up again. Originally, as soon as it would start droppin
g I'd turn on the electric boost pump but as it's happened more and more oft
en and I've become more brave, I've held off at least a few seconds and so f
ar it's always recovered before the engine started stumbling.
>
> I've never seen this happen with the boost pump on - just when the engine p
ump is working on its own. Though as I said, I don't normally fly with the b
oost pump on, so I obviously have less data with the boost pump on.
>
> What's particularly interesting is that it only seems to happen at higher a
ltitudes. Above 10000' or so, I can count on it happening at least once an h
our - at 13000', it sometimes happens every 10 or 15 minutes (though sometim
es it doesn't happen at all either for an hour). At 9500', I've seen it hap
pen only rarely, and I don't recall it ever occurring at 8500' or below.
>
> When it drops, it tends to fall over the course of about 5-10 seconds and t
hen climb back up over 5-10 seconds. The whole event is over with within 15
-20 seconds, and doesn't seem to "linger" at low PSI. I'm not sure if this i
s "real" or an artifact of sensor filtering of the EFIS.
>
> It isn't specific to when the engine is particularly hot - I always climb w
ith the boost pump on, so when the engine is running hotter I never see the i
ssue. This happens after I've been flying around at cruise power settings a
t altitude, often with a below freezing outside temperature and CHTs in the 3
10-350 range, and usually lean of peak burning in the neighbourhood of 10 gp
h.
>
> I have a blast tube aimed towards the fuel pump (though not a full shroud)
. I've even tried removing my gascolator screens in case they were potentia
lly restricting fuel flow.
>
> It's been suggested that perhaps my fuel pressure sensor is having issues.
I could certainly change it out, but since I haven't seen an issue with th
e electric boost pump on, and since it only seems to happen at altitude, I w
ould expect if it was a sensor issue neither of these two factors would have
an effect.
>
> Does anyone have any suggestions on what to try? I have tons of engine se
nsor data logged from the EFIS that I could send if helpful.
>
> I'm a bit apprehensive of changing out the fuel pump (in that I haven't do
ne so before and would want to ensure that a new one is installed correctly s
o I don't damage anything). Has anyone done that before and could offer any
advice? On the other hand, I've lived with this one issue for long enough a
nd as it's the one thing I'm not completely happy with, I would like to try a
nd finally resolve it so I can better trust things.
>
> Thanks for any advice!
>
> Dan
> ---
> Dan Charrois
> President, Syzygy Research & Technology
> Phone: 780-961-2213
>
>
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>
>
>
Message 4
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| Subject: | Re: Ongoing fuel pressure problems |
It is not that simple. What pressure you are talking about depends on where
in the system you are looking, what brand system you have, etc.
In general, the Bendix/Precision style injection system needs about 14-15
psi minimum at the input to the fuel servo. Pressures going to the fuel
divider will be lower, and the flow divider shuts down flow at around 4-5
psi to prevent run-on at idle cutoff. The amount of pressure at the inlet
is important to have the system function correctly, and to get good
atomization at the nozzles. While the engine may run at 9 psi, I'd not be
at all comfortable to see below 15.
I don't know what pressures the AFS system needs. The Continental system
works quite differently and needs very steady and precise pressures at the
inlet that have to be checked annually.
Kelly
Sent from my IBM-360 main frame
On Thu, Jun 14, 2018 at 6:06 PM, John MacCallum <john.maccallum@bigpond.com
>
wrote:
> Hi Dan,
> From a Video I watched about Fuel Injected engines as long as there is
> positive pressure above about 5 PSI at high fuel flows to the FI Servo th
e
> engine will run fine. The Video was from Tempest Aero parts and it talked
> about Engine driven Fuel Pumps and Boost Pumps. The Video was Titled,
=9CThe
> Amazing Ubiquitous Diaphragm Fuel Pump.=9D
>
> Anyway the Video said nothing to worry about down to about 9 psi. What
> type of boost pump do you have? My Andair Electric boost pump is in the
> tunnel and so is the red cube. I have no issues with inaccurate flow
> readings but I do occasionally get fuel pressure fluctuations in very hot
> weather. That is ambient ground temps above 35 C. I solve this by running
> the boost pump until at altitude and the OAT has dropped below 30 C.
>
> Cheers John MacCallum
> VH-DUU
>
>
Message 5
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| Subject: | Re: Ongoing fuel pressure problems |
My Lycoming came with an AVStar AVX-5VA1 injector. I'm not sure what "style" of
injection that implies (I'm very admittedly not an engine expert). Though in
the IO-540 series operator's manual I got with the engine, on page 3-9 they
mention a pressure range for the inlet to the fuel injector of 14-45 psi, so I've
considered that 14 is a minimum - though I'm much more comfortable when it
is closer to 20. When it gets down to less than 14, I get very nervous. Though
I've seen it down to 10 psi briefly while the engine kept running, it sure
doesn't give me the warm fuzzies when it does that.
I have the ES Airflow pump and red cube Van's supplied installed pretty much exactly
as described in section 37, other than the exception that I have an Andair
fuel valve installed instead of the Van's supplied one. Considering that I've
always figured the transducer would have a simple vane system to measure fuel
flow, I have to admit to not really understanding how it could be so easily
confused by the boost pump upstream (no matter how "pulse-y" it may be)... but
it is.
Dan
> On 2018-Jun-14, at 8:22 PM, Kelly McMullen <apilot2@gmail.com> wrote:
>
> It is not that simple. What pressure you are talking about depends on where in
the system you are looking, what brand system you have, etc.
> In general, the Bendix/Precision style injection system needs about 14-15 psi
minimum at the input to the fuel servo. Pressures going to the fuel divider will
be lower, and the flow divider shuts down flow at around 4-5 psi to prevent
run-on at idle cutoff. The amount of pressure at the inlet is important to have
the system function correctly, and to get good atomization at the nozzles.
While the engine may run at 9 psi, I'd not be at all comfortable to see below
15.
> I don't know what pressures the AFS system needs. The Continental system works
quite differently and needs very steady and precise pressures at the inlet that
have to be checked annually.
> Kelly
> Sent from my IBM-360 main frame
>
> On Thu, Jun 14, 2018 at 6:06 PM, John MacCallum <john.maccallum@bigpond.com>
wrote:
> Hi Dan,
> From a Video I watched about Fuel Injected engines as long as there is positive
pressure above about 5 PSI at high fuel flows to the FI Servo the engine will
run fine. The Video was from Tempest Aero parts and it talked about Engine
driven Fuel Pumps and Boost Pumps. The Video was Titled, The Amazing Ubiquitous
Diaphragm Fuel Pump.
>
> Anyway the Video said nothing to worry about down to about 9 psi. What type of
boost pump do you have? My Andair Electric boost pump is in the tunnel and so
is the red cube. I have no issues with inaccurate flow readings but I do occasionally
get fuel pressure fluctuations in very hot weather. That is ambient
ground temps above 35 C. I solve this by running the boost pump until at altitude
and the OAT has dropped below 30 C.
>
> Cheers John MacCallum
> VH-DUU
>
>
>
>
>
---
Dan Charrois
President, Syzygy Research & Technology
Phone: 780-961-2213
Message 6
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| Subject: | Re: Ongoing fuel pressure problems |
The one aspect I don't like about the design of the fuel lines in the
RV-10 is that they go uphill to the fuel selector, then down to the
filter and pump, then back uphill to the firewall and mechanical pump.
I believe this forces the system to develop sufficient negative pressure
at the mechanical pump to overcome the loop in the fuel system.
The Andair with an extension can be mounted fairly low, but is limited
by tubing bend radius and lines coming out the bottom.
I don't think your fuel cube location should affect the total flow.
However the location upstream of the mechanical pump will affect
responsiveness.
On 6/14/2018 10:31 PM, Dan Charrois wrote:
>
> My Lycoming came with an AVStar AVX-5VA1 injector. I'm not sure what "style"
of injection that implies (I'm very admittedly not an engine expert). Though
in the IO-540 series operator's manual I got with the engine, on page 3-9 they
mention a pressure range for the inlet to the fuel injector of 14-45 psi, so
I've considered that 14 is a minimum - though I'm much more comfortable when
it is closer to 20. When it gets down to less than 14, I get very nervous. Though
I've seen it down to 10 psi briefly while the engine kept running, it sure
doesn't give me the warm fuzzies when it does that.
>
> I have the ES Airflow pump and red cube Van's supplied installed pretty much
exactly as described in section 37, other than the exception that I have an Andair
fuel valve installed instead of the Van's supplied one. Considering that
I've always figured the transducer would have a simple vane system to measure
fuel flow, I have to admit to not really understanding how it could be so easily
confused by the boost pump upstream (no matter how "pulse-y" it may be)...
but it is.
>
> Dan
>
>> On 2018-Jun-14, at 8:22 PM, Kelly McMullen <apilot2@gmail.com> wrote:
>>
>> It is not that simple. What pressure you are talking about depends on where
in the system you are looking, what brand system you have, etc.
>> In general, the Bendix/Precision style injection system needs about 14-15 psi
minimum at the input to the fuel servo. Pressures going to the fuel divider
will be lower, and the flow divider shuts down flow at around 4-5 psi to prevent
run-on at idle cutoff. The amount of pressure at the inlet is important to
have the system function correctly, and to get good atomization at the nozzles.
While the engine may run at 9 psi, I'd not be at all comfortable to see below
15.
>> I don't know what pressures the AFS system needs. The Continental system works
quite differently and needs very steady and precise pressures at the inlet
that have to be checked annually.
>> Kelly
>> Sent from my IBM-360 main frame
>>
>> On Thu, Jun 14, 2018 at 6:06 PM, John MacCallum <john.maccallum@bigpond.com>
wrote:
>> Hi Dan,
>> From a Video I watched about Fuel Injected engines as long as there is positive
pressure above about 5 PSI at high fuel flows to the FI Servo the engine
will run fine. The Video was from Tempest Aero parts and it talked about Engine
driven Fuel Pumps and Boost Pumps. The Video was Titled, The Amazing Ubiquitous
Diaphragm Fuel Pump.
>>
>> Anyway the Video said nothing to worry about down to about 9 psi. What type
of boost pump do you have? My Andair Electric boost pump is in the tunnel and
so is the red cube. I have no issues with inaccurate flow readings but I do occasionally
get fuel pressure fluctuations in very hot weather. That is ambient
ground temps above 35 C. I solve this by running the boost pump until at altitude
and the OAT has dropped below 30 C.
>>
>> Cheers John MacCallum
>> VH-DUU
>>
>>
>>
>>
>>
>
>
>
> ---
> Dan Charrois
> President, Syzygy Research & Technology
> Phone: 780-961-2213
>
>
>
>
>
Message 7
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| Subject: | Re: Ongoing fuel pressure problems |
My only comment has to do with the totalizer showing a 50% error with the boost
pump on. I too have a stock setup, but mine shows a 4% error with the electric
pump on. I seem to recall the electric pump has a by-pass with a check valve.
Id make sure there are no issues around that pump and its plumbing.
--------
Bob Turner
RV-10 QB
Read this topic online here:
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