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Lycoming Engine Fuel Flow Problem...

 
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Matt Dralle
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Joined: 08 Nov 2005
Posts: 19876
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: 19876
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


- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List

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deej(at)deej.net
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PostPosted: Wed Nov 18, 2015 7:38 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote

On 11/17/2015 10:24 PM, Matt Dralle wrote:
Quote:
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?



Any of those are possible. One possibly easy check is to detach the
fuel line from the carb, and direct it into a container. Do a fuel flow
test to see how much fuel you are getting from the fuel system. That
should tell you if the problem is in the carb or the fuel delivery system.

-Dj
--
Dj Merrill - N1JOV - EAA Chapter 87
Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Glastar Flyer N866RH - http://deej.net/glastar/


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jmjones2000(at)mindspring
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PostPosted: Wed Nov 18, 2015 11:35 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote

Sounds like it could be a vacuum leak. Be sure to check your carburetor for security, cracks ect. Check the entire air delivery system from the carburetor to the tube attachments on the cylinders. If you have the angle valve engine, be sure to pay close attention to the intake tube Orings.

Justin



Quote:
On Nov 18, 2015, at 12:24, 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








- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
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jmjones2000(at)mindspring
Guest





PostPosted: Wed Nov 18, 2015 11:58 am    Post subject: Lycoming Engine Fuel Flow Problem... Reply with quote

I forgot to mention my train of thought that made me consider a vacuum leak. The low fuel flow numbers you are experiencing could be due to air being drawn into the engine somewhere other than the Venturi. If air bypasses the Venturi, it doesn't draw fuel in with, it resulting in a leaner fuel mixture.


Quote:
On Nov 19, 2015, at 04:34, Justin Jones <jmjones2000(at)mindspring.com> wrote:



Sounds like it could be a vacuum leak. Be sure to check your carburetor for security, cracks ect. Check the entire air delivery system from the carburetor to the tube attachments on the cylinders. If you have the angle valve engine, be sure to pay close attention to the intake tube Orings.

Justin

Quote:


> On Nov 18, 2015, at 12:24, 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







- The Matronics Engines-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Engines-List
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