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Lycoming Engine Fuel Flow Problem...

 
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Matt Dralle
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Joined: 08 Nov 2005
Posts: 25204
Location: Livermore CA USA
PostPosted: Tue Nov 17, 2015 7:26 pm    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
Dear Listers,

I flew the RV-6 tonight that has a 1660 hour Lycoming O-360A1A with a Hartzell CS prop. I flew it 7 hours over a 3-day period about a week and a half ago with no issues whatsoever. Tonight, on take off, the EGT's all climbed into the 1450's right after take off and the CHT's were in the 400-450 range. The mixture was full rich. The engine didn't seem to be underpowered or rough but the fuel flow was about 9-10 GPH when it should have been in the 17-19GPH range. On the downwind I tried fiddling with the mixture with no change in making it richer. The mixture did make it leaner. I switched from the right to the left fuel tanks with no change. I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX. Both were reading similarly low fuel flows at full throttle - 9-10gph. I didn't think to flip on the electric boost pump. But the flow definitely seemed restricted. The mixture control seems to have normal throw in and out and isn't binding and does lean the engine. I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be?

Mechanical Fuel Pump?

Something in the Carb?

Plugged fuel line?

??

Thanks for your feedback,

Matt

-
Matt Dralle

RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 260+ Hours TTSN - Version 2.0 Now Flying!

RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 350+ Hours - Full Flyer Mode!

Matt's Livermore Airport Live ATC Stream!
Check out the live ATC stream directly from my hangar at the Livermore
Airport. Includes both Tower and Ground transmissions. Archives too!
For entertainment purposes only. http://klvk.matronics.com

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Matt Dralle
Site Admin


Joined: 08 Nov 2005
Posts: 25204
Location: Livermore CA USA
PostPosted: Tue Nov 17, 2015 7:27 pm    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
Dear Listers,

I flew the RV-6 tonight that has a 1660 hour Lycoming O-360A1A with a Hartzell CS prop. I flew it 7 hours over a 3-day period about a week and a half ago with no issues whatsoever. Tonight, on take off, the EGT's all climbed into the 1450's right after take off and the CHT's were in the 400-450 range. The mixture was full rich. The engine didn't seem to be underpowered or rough but the fuel flow was about 9-10 GPH when it should have been in the 17-19GPH range. On the downwind I tried fiddling with the mixture with no change in making it richer. The mixture did make it leaner. I switched from the right to the left fuel tanks with no change. I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX. Both were reading similarly low fuel flows at full throttle - 9-10gph. I didn't think to flip on the electric boost pump. But the flow definitely seemed restricted. The mixture control seems to have normal throw in and out and isn't binding and does lean the engine. I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be?

Mechanical Fuel Pump?

Something in the Carb?

Plugged fuel line?

??

Thanks for your feedback,

Matt

-
Matt Dralle

RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 260+ Hours TTSN - Version 2.0 Now Flying!

RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 350+ Hours - Full Flyer Mode!

Matt's Livermore Airport Live ATC Stream!
Check out the live ATC stream directly from my hangar at the Livermore
Airport. Includes both Tower and Ground transmissions. Archives too!
For entertainment purposes only. http://klvk.matronics.com

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Kellym



Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ
PostPosted: Tue Nov 17, 2015 8:10 pm    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
You are correct. The FF is too low and it is reflected on the EGT and
CHT. In fact, you undoubtedly were LOP, producing about 140-150hp. A bit
surprising if it in fact still has a carburetor.
IMHO, if EGT goes above 1350 on takeoff roll, it is cause to abort if
feasible. It should be between 1200 and 1300, assuming sea level vicinity.
Plugged fuel filter, failing mechanical pump diaphram, carb fuel inlet
needle valve stuck, carb fuel vent plugged are all potential causes. If
there is any seepage on the mech pump drain, the diaphram is bad and not
generating the fuel pressure needed. The carb may or maynot have an
inlet screen that could be partially plugged. If the data goes back far
enough I would download the log from the Skyview and look for when the
problem first occurred. That may help you isolate when/where it happened
and what changed.

On 11/17/2015 8:24 PM, Matt Dralle wrote:
Quote:

Dear Listers,

I flew the RV-6 tonight that has a 1660 hour Lycoming O-360A1A with a Hartzell CS prop. I flew it 7 hours over a 3-day period about a week and a half ago with no issues whatsoever. Tonight, on take off, the EGT's all climbed into the 1450's right after take off and the CHT's were in the 400-450 range. The mixture was full rich. The engine didn't seem to be underpowered or rough but the fuel flow was about 9-10 GPH when it should have been in the 17-19GPH range. On the downwind I tried fiddling with the mixture with no change in making it richer. The mixture did make it leaner. I switched from the right to the left fuel tanks with no change. I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX. Both were reading similarly low fuel flows at full throttle - 9-10gph. I didn't think to flip on the electric boost pump. But the flow definitely seemed restricted. The mixture control seems to have normal throw in and out a!
nd isn't binding and does lean the engine. I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be?

Mechanical Fuel Pump?

Something in the Carb?

Plugged fuel line?

??

Thanks for your feedback,

Matt

-
Matt Dralle

RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 260+ Hours TTSN - Version 2.0 Now Flying!

RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 350+ Hours - Full Flyer Mode!

Matt's Livermore Airport Live ATC Stream!
Check out the live ATC stream directly from my hangar at the Livermore
Airport. Includes both Tower and Ground transmissions. Archives too!
For entertainment purposes only. http://klvk.matronics.com


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recapen(at)earthlink.net
Guest
PostPosted: Tue Nov 17, 2015 8:10 pm    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
Sounds like you have a blockage in your fuel filters that just barely allows enough fuel to flow.....

I had a similar issue with my AFP injected IO360B1F6. There is a small fuel inlet filter that was clogged with fine black goo. Cleaned that and added a larger capacity filter upstream that has a smaller micron rating than the inlet filter - it is on my annual list now.

Cured the issue for me.

Glad you had enough fuel flow to continue flying and safely land. Throttling back helped me - I didn't experience mine on take off though.....boost pump didn't help me....

--

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vanremog(at)aol.com
Guest
PostPosted: Tue Nov 17, 2015 10:49 pm    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
Have you cleaned all your screens?
Did you switch tanks?
Did you check your vents?
-GV

Sent from a galaxy far far away...

Matt Dralle <dralle(at)matronics.com> wrote:

--> RV-List message posted by: Matt Dralle <dralle(at)matronics.com>
Dear Listers,

I flew the RV-6 tonight that has a 1660 hour Lycoming O-360A1A with a Hartzell CS prop.  I flew it 7 hours over a 3-day period about a week and a half ago with no issues whatsoever.  Tonight, on take off, the EGT's all climbed into the 1450's right after take off and the CHT's were in the 400-450 range.  The mixture was full rich.  The engine didn't seem to be underpowered or rough but the fuel flow was about 9-10 GPH when it should have been in the 17-19GPH range.  On the downwind I tried fiddling with the mixture with no change in making it richer.  The mixture did make it leaner.  I switched from the right to the left fuel tanks with no change.  I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX.  Both were reading similarly low fuel flows at full throttle - 9-10gph.  I didn't think to flip on the electric boost pump.  But the flow definitely seemed restricted.  The mixture control seems to have normal throw in and out a!
nd isn't binding and does lean the engine.  I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be? 

Mechanical Fuel Pump?

Something in the Carb?

Plugged fuel line?

??

Thanks for your feedback,

Matt

-
Matt Dralle

RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 260+ Hours TTSN - Version 2.0 Now Flying!

RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 350+ Hours - Full Flyer Mode!

Matt's Livermore Airport Live ATC Stream!
Check out the live ATC stream directly from my hangar at the Livermore
Airport.  Includes both Tower and Ground transmissions.  Archives too!
For entertainment purposes only.  http://klvk.matronics.com

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n146wb(at)cfu.net
Guest
PostPosted: Wed Nov 18, 2015 5:04 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
Admittedly, with all the readings on your monitoring giving abnormal numbers, it appears to be be a problem with the fuel system, but I would first check to see that the problem is real. Do you know what the engine pulled for static rpm, wot on the ground before the problem showed up? If so, then I would check the wot rpm now to see if you are getting full power. Did you fly long enough to check your real fuel usage by refueling and comparing usage against what you would normally expect? If you seem to get full rpm (power) and real fuel usage is normal then there MIGHT be an electrical problem that's affecting your monitoring system, like a bad ground.

Warren

Quote:
On Nov 18, 2015, at 12:48 AM, vanremog(at)aol.com wrote:

switched from the right to the left fuel tanks with no change. I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX. Both were reading similarly low fuel flows at full throttle - 9-10gph. I didn't think to flip on the electric boost pump. But the flow definitely seemed restricted. The mixture control seems to have normal throw in and out a!
nd isn't binding and does lean the engine. I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be?

Mechanical Fuel Pump?


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denis.walsh(at)comcast.ne
Guest
PostPosted: Wed Nov 18, 2015 8:39 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
I have a similar set up with an A1A. Your observations and deductions seem logical to me. I would do the easiest thing first, and check the boost pump on to see if it brings up the flow/pressure. This would point to the mechanical pump as a problem.

By the way, it is my opinion that you should always take off with the boost pump on. I also use a procedure by which I check the boost pump for pressure before engine start, then start with only the mechanical pump. When the run up is complete, Then I turn on the boost pump for take off. Again this is another chance to catch a failed or failing mech pump before take off.

Hope this helps.
Denis Walsh
denis.walsh(at)comcast.net

Quote:
On 17Nov, 2015, at 20:24, Matt Dralle <dralle(at)matronics.com> wrote:




Dear Listers,

I flew the RV-6 tonight that has a 1660 hour Lycoming O-360A1A with a Hartzell CS prop. I flew it 7 hours over a 3-day period about a week and a half ago with no issues whatsoever. Tonight, on take off, the EGT's all climbed into the 1450's right after take off and the CHT's were in the 400-450 range. The mixture was full rich. The engine didn't seem to be underpowered or rough but the fuel flow was about 9-10 GPH when it should have been in the 17-19GPH range. On the downwind I tried fiddling with the mixture with no change in making it richer. The mixture did make it leaner. I switched from the right to the left fuel tanks with no change. I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX. Both were reading similarly low fuel flows at full throttle - 9-10gph. I didn't think to flip on the electric boost pump. But the flow definitely seemed restricted. The mixture control seems to have normal throw in and out a!
nd isn't binding and does lean the engine. I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be?

Mechanical Fuel Pump?

Something in the Carb?

Plugged fuel line?

??

Thanks for your feedback,

Matt

-
Matt Dralle

RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 260+ Hours TTSN - Version 2.0 Now Flying!

RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 350+ Hours - Full Flyer Mode!

Matt's Livermore Airport Live ATC Stream!
Check out the live ATC stream directly from my hangar at the Livermore
Airport. Includes both Tower and Ground transmissions. Archives too!
For entertainment purposes only. http://klvk.matronics.com








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recapen(at)earthlink.net
Guest
PostPosted: Wed Nov 18, 2015 10:23 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
Denis,

I use your method for take-offs also!

Ralph

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Matt Dralle
Site Admin


Joined: 08 Nov 2005
Posts: 25204
Location: Livermore CA USA
PostPosted: Wed Nov 18, 2015 11:40 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote
I switched tanks with no change in flow. So it would seem to not to be related to the fuel tanks or their plumbing specifically. I'm anxious to dig in and figure out what's going on...

Matt
At 10:48 PM 11/17/2015 Tuesday, you wrote:
Quote:
Have you cleaned all your screens?
Did you switch tanks?
Did you check your vents?
-GV
Sent from a galaxy far far away...
Matt Dralle <dralle(at)matronics.com> wrote:


Dear Listers,

I flew the RV-6 tonight that has a 1660 hour Lycoming O-360A1A with a Hartzell CS prop. I flew it 7 hours over a 3-day period about a week and a half ago with no issues whatsoever. Tonight, on take off, the EGT's all climbed into the 1450's right after take off and the CHT's were in the 400-450 range. The mixture was full rich. The engine didn't seem to be underpowered or rough but the fuel flow was about 9-10 GPH when it should have been in the 17-19GPH range. On the downwind I tried fiddling with the mixture with no change in making it richer. The mixture did make it leaner. I switched from the right to the left fuel tanks with no change. I have two fuel flow transducers one feeding the Skyview and the other feeding a Matronics FuelChec DX. Both were reading similarly low fuel flows at full throttle - 9-10gph. I didn't think to flip on the electric boost pump. But the flow definitely seemed restricted. The mixture control seems to have normal throw in and out a
!

Quote:
nd isn't binding and does lean the engine. I came in and landed with no issues.

I haven't pulled the cowling yet to have a look to see if its something obvious with the mixture cable, but what are some thoughts on what this could be?

Mechanical Fuel Pump?

Something in the Carb?

Plugged fuel line?

??

Thanks for your feedback,

Matt

-
Matt Dralle

RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 260+ Hours TTSN - Version 2.0 Now Flying!

RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 350+ Hours - Full Flyer Mode!

Matt's Livermore Airport Live ATC Stream!
Check out the live ATC stream directly from my hangar at the Livermore
Airport. Includes both Tower and Ground transmissions. Archives too!
For entertainment purposes only. http://klvk.matronics.com


Matt G Dralle | Matronics | 581 Jeannie Way | Livermore | CA | 94550
925-606-1001 V | 925-606-6281 F | dralle(at)matronics.com Email
http://www.matronics.com/ WWW | Featuring Products For Aircraft

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