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  #1  
Old 12-06-2017, 06:38 PM
Phantom30's Avatar
Phantom30 Phantom30 is offline
 
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Location: Coeur d'Alene, ID/Casa Grande, AZ
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Default Fuel pressure problems

Guys..I need help trying to understand Vanís RV-12 fuel flow system. In looking at the plans 46...specifically the multiple bango fitting thingy where the fuel supply from the engine driven pump feeds, the supply for both carbs branch off...then the upper w/flow metering jet controls flow return to the fuel tank.

My question is....is the fuel pressure sensor take-off before or after the flow restrictor? By looking at the figure drawing...the restritor is installed controlling flow to both return and pressure sensor.

Scott..help (iím Chasing grimlins)
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Ric Dickison
307 (CAB) Phantom
Search and Destroy (Can
Tho RVN)
Distinguished Flying Cross Society Member
CH-47 & UH-1H "Driver"
Rotax 9 Series Service IRMT

RV-12 Kit#729 "N312RD" is now a full functioning fun machine!! Thanks Van for fulfilling my dream😎
2017 Dues Paid
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  #2  
Old 12-06-2017, 06:55 PM
Azjulian Azjulian is offline
 
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Location: Scottsdale, Arizona
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Default

Hi Ric - the line of the fuel pressure sensor, the return and the two carbs all come of the fuel distribution block. The restrictor is in the return line hose and only restricts return fuel back to the tank.

I'm Mark Winslows friend and he has my contact details, so please call if I can help you in any way.

Julian
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  #3  
Old 12-06-2017, 10:27 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Default

Quote:
Originally Posted by Phantom30 View Post
Guys..I need help trying to understand Van’s RV-12 fuel flow system. In looking at the plans 46...specifically the multiple bango fitting thingy where the fuel supply from the engine driven pump feeds, the supply for both carbs branch off...then the upper w/flow metering jet controls flow return to the fuel tank.

My question is....is the fuel pressure sensor take-off before or after the flow restrictor? By looking at the figure drawing...the restritor is installed controlling flow to both return and pressure sensor.

Scott..help (i’m Chasing grimlins)
If everything is assembled correctly the fuel that feeds both carbs and the pressure sensor is before/upstream of the restrictor.

The restrictor is inside of the double banjo fitting on the top of the block.
The actual restrictor is inside the hose barb leg that the return hose going to the firewall fitting is connected too. If this hose assemble is installed backwards (so that the restrictor is on the pressure sensor leg) the system pressure will be very low because there is an unrestricted flow path via the return line back to the tank.

I don't remember the details (and don't have plans at home) but I think there might be a restrictor that is supposed to be removed from the bore of the banjo bolt when the double banjo fitting is added to the top.

Edit - Found it Page 46-09 at this link http://www.vansaircraft.com/pdf/revi...2/RV-12_46.pdf
Page 46-07 is where it instructs the builder to remove the pilot jet (restrictor).
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Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 12-07-2017 at 09:40 AM.
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  #4  
Old 12-07-2017, 08:57 AM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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Default NOT wanting to open the flame war again--

but the restrictor in the double banjo was one of the reasons Steve and I came up with our teflon hose package. Yes, with 2 hoses that were fairly close in length, we found some builders were installing it backwards--yep with some effort since one of the hoses is shorter. So we made an attempt to eliminate that possibility.
On the same note-- the other reason we looked into this was the RTV sealing of the hose and firesleeve area at the banjo. We found several builders were PULLING the firesleeve out of the bands, AND pulling the hose (rubber at that time) off the banjo stems. This was tearing the liner of the hose, since the barbs are designed to lock the hose in place. Some builders were sealing the ends and pushing the hose back on the barbs with a damaged end of the hose. Some even had some fuel leaks after reclamping due to the torn hose liners.
That was the big reason we designed our kit package- to try to eliminate the possibility of damaging the hose. GRANTED----there were many builders that had no issues at all, and everything was fine---we have one at 3J1. It was the others that we made our teflon hose package for.

Tom
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Tom Swearengen, TS Flightlines LLC
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com
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  #5  
Old 12-07-2017, 09:34 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by TS Flightlines View Post
but the restrictor in the double banjo was one of the reasons Steve and I came up with our teflon hose package. Yes, with 2 hoses that were fairly close in length, we found some builders were installing it backwards--yep with some effort since one of the hoses is shorter. So we made an attempt to eliminate that possibility.
On the same note-- the other reason we looked into this was the RTV sealing of the hose and firesleeve area at the banjo. We found several builders were PULLING the firesleeve out of the bands, AND pulling the hose (rubber at that time) off the banjo stems. This was tearing the liner of the hose, since the barbs are designed to lock the hose in place. Some builders were sealing the ends and pushing the hose back on the barbs with a damaged end of the hose. Some even had some fuel leaks after reclamping due to the torn hose liners.
That was the big reason we designed our kit package- to try to eliminate the possibility of damaging the hose. GRANTED----there were many builders that had no issues at all, and everything was fine---we have one at 3J1. It was the others that we made our teflon hose package for.

Tom
I am not clear on why a more expensive hose is justification to prevent someone from installing a hose incorrectly, when the instructions are very clear about saying "use caution, this hose can be installed backwards", and then goes on to explain in clear detail how to double check that it is correct.

As for the RVT reason....
This hose assembly was redesigned many years ago (eliminating the RTV sealing process and any tendency for the hose to separate) so that hasn't even been an issue for a long time.
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Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #6  
Old 12-07-2017, 10:34 AM
TS Flightlines TS Flightlines is offline
 
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Default Scott--

"I am not clear on why a more expensive hose is justification to prevent someone from installing a hose incorrectly, when the instructions are very clear about saying "use caution, this hose can be installed backwards", and then goes on to explain in clear detail how to double check that it is correct.

As for the RVT reason....
This hose assembly was redesigned many years ago (eliminating the RTV sealing process and any tendency for the hose to separate) so that hasn't even been an issue for a long time."

We didnt do it to keep someone from installing the hose backwards, even though YES is was clearly labeled, but guys were doing it anyway. Big reason was to use a teflon hose to eliminate the rubber hose liner deterioration that was happening at the time with the fuel additives. Guess thats why Rotax went to teflon for the carb hoses, and I assume thats what the new Rotax fuel hose assembly is. Is the VA216 assembly now rubber or teflon? And is the gascolator to fuel pump hose still rubber, or is it now teflon?

YES the RTV thing was many years ago---circa 2011, and YES it has been rectified.

Again----not wanting to get into a flame war here.

Tom
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Tom Swearengen, TS Flightlines LLC
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com
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  #7  
Old 12-07-2017, 11:37 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by TS Flightlines View Post

We didnt do it to keep someone from installing the hose backwards, even though YES is was clearly labeled, but guys were doing it anyway.
Ok, but it seemed like that is what you said.....

Quote:
Originally Posted by TS Flightlines View Post
but the restrictor in the double banjo was one of the reasons Steve and I came up with our teflon hose package. Yes, with 2 hoses that were fairly close in length, we found some builders were installing it backwards--yep with some effort since one of the hoses is shorter. So we made an attempt to eliminate that possibility.



I believe the updated version VA-216 is teflon.

The gascolator to engine driven fuel pump hose is part of the engine as supplied by Rotax. The current version is teflon
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Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 12-07-2017 at 12:49 PM.
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  #8  
Old 12-07-2017, 06:30 PM
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Phantom30 Phantom30 is offline
 
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Default

Quote:
Originally Posted by rvbuilder2002 View Post
If everything is assembled correctly the fuel that feeds both carbs and the pressure sensor is before/upstream of the restrictor.

The restrictor is inside of the double banjo fitting on the top of the block.
The actual restrictor is inside the hose barb leg that the return hose going to the firewall fitting is connected too. If this hose assemble is installed backwards (so that the restrictor is on the pressure sensor leg) the system pressure will be very low because there is an unrestricted flow path via the return line back to the tank.

I don't remember the details (and don't have plans at home) but I think there might be a restrictor that is supposed to be removed from the bore of the banjo bolt when the double banjo fitting is added to the top.

Edit - Found it Page 46-09 at this link http://www.vansaircraft.com/pdf/revi...2/RV-12_46.pdf
Page 46-07 is where it instructs the builder to remove the pilot jet (restrictor).
Thanks Scott...couldnít figure where the restrictor was located...

Now, too add a mechincal pressure port for 0-10 psi gauge too verify sensor reading...but starting to suspect ďcrapĒ is pugging the bango fittings.
__________________
Ric Dickison
307 (CAB) Phantom
Search and Destroy (Can
Tho RVN)
Distinguished Flying Cross Society Member
CH-47 & UH-1H "Driver"
Rotax 9 Series Service IRMT

RV-12 Kit#729 "N312RD" is now a full functioning fun machine!! Thanks Van for fulfilling my dream😎
2017 Dues Paid
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  #9  
Old 12-08-2017, 09:35 AM
TS Flightlines TS Flightlines is offline
 
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Ric---install a temporary TEE just before the pressure sender. That way you can read both pressures at the same time.

Why do you suspect '****' plugging the banjos? Are you seeing bits of black residue in the hoses?
Be sure to let us know!
Tom
__________________
Tom Swearengen, TS Flightlines LLC
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com
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  #10  
Old 12-08-2017, 01:53 PM
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Phantom30 Phantom30 is offline
 
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Quote:
Originally Posted by TS Flightlines View Post
Ric---install a temporary TEE just before the pressure sender. That way you can read both pressures at the same time.

Why do you suspect '****' plugging the banjos? Are you seeing bits of black residue in the hoses?
Be sure to let us know!
Tom
Now, really stumped. Put a mechanical gauge in place of psi sensor. Flow tested (using aux pump) at feed to new mechanical pump (got 1/2 gal in 90 seconds) which equals 20gal/hour....should be plenty🙄

Pulled bango fittings top/bottom to check for pluggage....none. Ran engine..got same results @ 5200 rpm sucked pressure down to less than 1 psi.

Pulled fuel tank return line loose @ fire wall...plugged to stop flow...restart engine...same results. Iím stumped....help?
__________________
Ric Dickison
307 (CAB) Phantom
Search and Destroy (Can
Tho RVN)
Distinguished Flying Cross Society Member
CH-47 & UH-1H "Driver"
Rotax 9 Series Service IRMT

RV-12 Kit#729 "N312RD" is now a full functioning fun machine!! Thanks Van for fulfilling my dream😎
2017 Dues Paid
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