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Fuel Pump Issue
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Bajajim

Joined: 21 Aug 2012
Posts: 30

Posted: Mon Oct 28, 2013 8:56 am Post subject: Fuel Pump Issue

I seem to have the same problem when the RV10 is in warmer climates (Hangar

in Las Vegas)... I take off out of colder climates Parowan Utah (5970 MSL)

32 degrees or so (with Cool Fuel) and the problem seems to disappear.

I replaced the mechanical fuel pump about 30 hours ago thinking it was the

pump.

No change with the new pump.

Fuel flow always remains the same, Boost pump makes the pressure issue go

away...



Jim Villani

Kit# 41084 

N10KQ

142.7 and counting

Jim(at)JimVillani.com 



--

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Oct 28, 2013 9:07 am Post subject: Fuel Pump Issue

I suspect that some of the fuel pump issues are the fuel line rise to the selector valve as Van's  plans call for. Some of us have worked to lower the valve as much as possible in the tunnel to reduce the uphill pull from the tanks. The mechanical pump can only generate about 1-2 psi of suction to pull fuel over that rise. Lowering the fuel pressure with that suction is going to make it easier for fuel to vaporize and create bubbles in the line. Pump does not do well with bubbles.

 

On Mon, Oct 28, 2013 at 9:53 AM, JimVillani <Jim(at)jimvillani.com (Jim(at)jimvillani.com)> wrote:

 [quote]--> RV10-List message posted by: "JimVillani" <Jim(at)jimvillani.com (Jim(at)jimvillani.com)>

  

 I seem to have the same problem when the RV10 is in warmer climates (Hangar

 in Las Vegas)... I take off out of colder climates Parowan Utah (5970 MSL)

 32 degrees or so (with Cool Fuel) and the problem seems to disappear.

 I replaced the mechanical fuel pump about 30 hours ago thinking it was the

 pump.

 No change with the new pump.

 Fuel flow always remains the same, Boost pump makes the pressure issue go

 away...

 

 Jim Villani

 Kit# 41084

 N10KQ

 142.7 and counting

 Jim(at)JimVillani.com

 

 

 

 --

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Mon Oct 28, 2013 9:43 am Post subject: Re: Fuel Pump Issue

I'm using an Andair selector and the valve is pretty low in the tunnel as I had to buy an extender to reach it. Have occasionally seen engine stumble during very high AOA stall work if electric full pump is not running. Same when switching fuel tanks, but not always. Is 18psi fuel pressure off mechanical within "normal" range? 



Thanks,

Jay

N433RV - flying

rnewman(at)tcwtech.com
Guest

Posted: Mon Oct 28, 2013 10:49 am Post subject: Fuel Pump Issue

You may want to read over this write up I did last year on this issue.   I think this may be your issue.  

http://tcwtech.com/Fuel%20flow%20write-up.pdf



Bob Newman

N541RV



Sent from my iPhone



On Oct 28, 2013, at 7:42 AM, "hotwheels" <jaybrinkmeyer(at)yahoo.com (jaybrinkmeyer(at)yahoo.com)> wrote:

[quote]--> RV10-List message posted by: "hotwheels" <jaybrinkmeyer(at)yahoo.com (jaybrinkmeyer(at)yahoo.com)>



I went out on a weekend x-country flight (6 hours) and noticed some strange behavior.



In cruise, my fuel flow readings would occasionally fluctuate between 9.5 and 10.5 gph without me touching anything... At the same time, the fuel psi changed from ~18 (normal) and 14psi. At 14 the engine would stumble. Same behavior on either tank... even after richening the mixture. Turning on the electric fuel pump caused the symptom to go away. No obvious leaks and no fuel smells.



I'm wondering if I too have an issue lurking in the pump department. It's nearly time for my annual, so it's good timing as everything has to come apart anyway. 



Jay

N433RV - flying





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=411584#411584

http://www.matronics.com/Navigator?RV10-List

http://forums.matr====================================================sp;                        &nbsp href="http://www.matronics.com/contribution">http://www.matronics.com/con=============================================





[b]

flysrv10(at)gmail.com
Guest

Posted: Mon Oct 28, 2013 11:06 am Post subject: Fuel Pump Issue

I have my fuel system set up exactly as plans show and I have only had one occasion in stinking hot hot weather during climb, that I felt a small rumble with engine missing.  Turning the fuel pump on fixed the issue immediately.



I do have one modification to the tunnel due to Florida's heat; one of my cabin heat hoses actually pumps fresh air into the tunnel and reduces the temperature from scolding hot to bearable on the tunnel walls.

My set up points the issue to tunnel heat than anything else.

Do not archive.

 Rob Kermanj

772-418-1417

  

 

On Oct 28, 2013, at 2:48 PM, Tcwtech <rnewman(at)tcwtech.com (rnewman(at)tcwtech.com)> wrote:

[quote]You may want to read over this write up I did last year on this issue.   I think this may be your issue.  

http://tcwtech.com/Fuel%20flow%20write-up.pdf



Bob Newman

N541RV



Sent from my iPhone



On Oct 28, 2013, at 7:42 AM, "hotwheels" <jaybrinkmeyer(at)yahoo.com (jaybrinkmeyer(at)yahoo.com)> wrote:

 	  Quote: 	
		  --> RV10-List message posted by: "hotwheels" <jaybrinkmeyer(at)yahoo.com (jaybrinkmeyer(at)yahoo.com)>



I went out on a weekend x-country flight (6 hours) and noticed some strange behavior.



In cruise, my fuel flow readings would occasionally fluctuate between 9.5 and 10.5 gph without me touching anything... At the same time, the fuel psi changed from ~18 (normal) and 14psi. At 14 the engine would stumble. Same behavior on either tank... even after richening the mixture. Turning on the electric fuel pump caused the symptom to go away. No obvious leaks and no fuel smells.



I'm wondering if I too have an issue lurking in the pump department. It's nearly time for my annual, so it's good timing as everything has to come apart anyway. 



Jay

N433RV - flying





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=411584#411584

http://www.matronics.com/Navigator?RV10-List

http://forums.matr===========================sp;                          href="http://www.matronics.com/contribution">http://www.matronics.com/con=============================================



	
  	  Quote: 	
		  



new,courier">http://www.matronics.com/Navigator?RV10-List

href="http://forums.matronics.com/">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	


[b]

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Mon Oct 28, 2013 11:28 am Post subject: Re: Fuel Pump Issue

The physicist in me feels compelled to point out that the fuel pump does not pull fuel up to the fuel valve. This is like a siphon; atmospheric air pressure is sufficient to push the fuel up to the valve, and back to the tunnel floor. However, the conclusion that pressure is reduced at the high point is correct.



I have a stock Vans setup and have never seen anything like a vapor lock issue, including some very hot weather flying. But I also have the post 2008 setup where Vans lowered the fuel valve location. Do those seeing problems have the earlier, higher mounted valves?

_________________
Bob Turner
RV-10 QB

rnewman(at)tcwtech.com
Guest

Posted: Mon Oct 28, 2013 11:52 am Post subject: Fuel Pump Issue

I have the Andair valve mounted low in the tunnel actuated by an extension arm a few inches long. 



Bob Newman 

Sent from my iPhone



On Oct 28, 2013, at 1:28 PM, "Bob Turner" <bobturner(at)alum.rpi.edu> wrote:



 	  Quote: 	
		   

 

 The physicist in me feels compelled to point out that the fuel pump does not pull fuel up to the fuel valve. This is like a siphon; atmospheric air pressure is sufficient to push the fuel up to the valve, and back to the tunnel floor. However, the conclusion that pressure is reduced at the high point is correct.

 

 I have a stock Vans setup and have never seen anything like a vapor lock issue, including some very hot weather flying. But I also have the post 2008 setup where Vans lowered the fuel valve location. Do those seeing problems have the earlier, higher mounted valves?

 

 --------

 Bob Turner

 RV-10 QB

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=411621#411621

bwestfall

Joined: 22 Oct 2008
Posts: 131
Location: Portland, OR

Posted: Mon Oct 28, 2013 11:59 am Post subject: Fuel Pump Issue

Is the "rise" a cumulative effect or overall from the tanks to engine driven

pump?  I would think that the rise from the electric pump to the firewall AN

fitting is greater than the rise from tunnel floor to the valve body.  If

cumulative then maybe the two put together is an issue?



-Ben

--

rleffler

Joined: 05 Nov 2006
Posts: 680

Posted: Mon Oct 28, 2013 12:35 pm Post subject: Fuel Pump Issue

I have the same



Sent from my iPhone



On Oct 28, 2013, at 3:52 PM, Tcwtech <rnewman(at)tcwtech.com> wrote:






I have the Andair valve mounted low in the tunnel actuated by an extension arm a few inches long. 



Bob Newman 

Sent from my iPhone



 	  Quote: 	
		   On Oct 28, 2013, at 1:28 PM, "Bob Turner" <bobturner(at)alum.rpi.edu> wrote:

 

 

 

 The physicist in me feels compelled to point out that the fuel pump does not pull fuel up to the fuel valve. This is like a siphon; atmospheric air pressure is sufficient to push the fuel up to the valve, and back to the tunnel floor. However, the conclusion that pressure is reduced at the high point is correct.

 

 I have a stock Vans setup and have never seen anything like a vapor lock issue, including some very hot weather flying. But I also have the post 2008 setup where Vans lowered the fuel valve location. Do those seeing problems have the earlier, higher mounted valves?

 

 --------

 Bob Turner

 RV-10 QB

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=411621#411621

_________________
Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Oct 28, 2013 1:09 pm Post subject: Fuel Pump Issue

Bob,

Very well written explanation of at least one factor in the problem. Not to mention that having the FF sending unit in the tunnel introduces two more connections in the tunnel that could leak.

 

Van's reasoning is rather faulty in my view, since the red cube is FAA certified for use in the engine compartment, and in fact the STC that I have on my Mooney using the same sending unit requires the sending unit between the mechanical pump and the fuel servo on certified planes without a return line, and between the servo and the flow divider on planes with a return line.

 

Also, IMHO, 18 PSI is inadequate for normal operation. My Mooney with IO-360 and the same pump sees 24-25 PSI as normal from fuel flow of 8 gph up to 18 gph, with normal cruise around 10 gph on mechanical pump only. Boost pump will add 1-2 psi with engine running.

 

14 psi is the absolute minimum for the Bendix RSA fuel injection, with 45 max. 



Unless I am looking at my fuselage crooked the stock Van's selector location is near the full fuel level  of the tanks and way above the empty tank level, so gravity at less than something like 3/4 tank is not going to provide any flow of fuel through the selector without some initiating suction and a siphon to keep it going. Introduce any air or vapor and the siphon will be lost.

 

On Mon, Oct 28, 2013 at 11:48 AM, Tcwtech <rnewman(at)tcwtech.com (rnewman(at)tcwtech.com)> wrote:

  	  Quote: 	
		  You may want to read over this write up I did last year on this issue.   I think this may be your issue.  

 



http://tcwtech.com/Fuel%20flow%20write-up.pdf



Bob Newman

N541RV



Sent from my iPhone

 

On Oct 28, 2013, at 7:42 AM, "hotwheels" <jaybrinkmeyer(at)yahoo.com (jaybrinkmeyer(at)yahoo.com)> wrote:



 	  Quote: 	
		   --> RV10-List message posted by: "hotwheels" <jaybrinkmeyer(at)yahoo.com (jaybrinkmeyer(at)yahoo.com)>

I went out on a weekend x-country flight (6 hours) and noticed some strange behavior.

 

In cruise, my fuel flow readings would occasionally fluctuate between 9.5 and 10.5 gph without me touching anything... At the same time, the fuel psi changed from ~18 (normal) and 14psi. At 14 the engine would stumble. Same behavior on either tank... even after richening the mixture. Turning on the electric fuel pump caused the symptom to go away. No obvious leaks and no fuel smells.

 

I'm wondering if I too have an issue lurking in the pump department. It's nearly time for my annual, so it's good timing as everything has to come apart anyway. 

 

Jay

N433RV - flying





Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=411584#411584

 



http://www.matronics.com/Navigator?RV10-List

 http://forums.matr===========================sp;                        &nbsp href="http://www.matronics.com/contribution">http://www.matronics.com/con====================

 



	
  	  Quote: 	
		  



get="_blank">http://www.matronics.com/Navigator?RV10-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




	


-- 



 - sent from the microchip implanted in my forearm

  

  [quote][b]

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

rv10flyer(at)live.com
Guest

Posted: Mon Oct 28, 2013 5:03 pm Post subject: Fuel Pump Issue

I have a post 2008 and I have seen fuel pressure issues in a climb once out 

of 101F in Arizona and after a 2nd takeoff in 90F SoCal, right after 

refueling. In both cases the VP-200 threw in the autoboost and it was gone. 

It happens, but rarely. Engine has no idea there is a problem or it doesnâ€™t 

sound like it does anyway



My biggest issue remains the fuel flow- it will vary from 10.2gph to 9.9 

without changing a thing, than go back up to 10.1 and back and forth 

in-between.

Pascal



--

arplnplt(at)gmail.com
Guest

Posted: Mon Oct 28, 2013 6:55 pm Post subject: Fuel Pump Issue

I see 24 psi from my mechanical pump.  28 or so for electric.



Dave Leikam



On Oct 28, 2013, at 12:43 PM, hotwheels <jaybrinkmeyer(at)yahoo.com> wrote:



 	  Quote: 	
		   

 

 I'm using an Andair selector and the valve is pretty low in the tunnel as I had to buy an extender to reach it. Have occasionally seen engine stumble during very high AOA stall work if electric full pump is not running. Same when switching fuel tanks, but not always. Is 18psi fuel pressure off mechanical within "normal" range? 

 

 Thanks,

 Jay

 N433RV - flying

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=411613#411613

dave.saylor.aircrafters(a
Guest

Posted: Tue Oct 29, 2013 7:49 am Post subject: Fuel Pump Issue

This might be semantics but that looks like a +/-1.5% fluctuation. Â Assuming you're using a red cube, EI claims 2%, but they don't say if it's +/- or overall. Â I see similar fluctuations. Â I figured it was just noise.

   Dave Saylor

[url=tel:831-750-0284]831-750-0284[/url] CL

 



On Mon, Oct 28, 2013 at 6:02 PM, Pascal <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

[quote]   --> RV10-List message posted by: "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)>

 

 I have a post 2008 and I have seen fuel pressure issues in a climb once out of 101F in Arizona and after a 2nd takeoff in 90F SoCal, right after refueling. In both cases the VP-200 threw in the autoboost and it was gone. It happens, but rarely. Engine has no idea there is a problem or it doesnâ€™t sound like it does anyway

    

 My biggest issue remains the fuel flow- it will vary from 10.2gph to 9.9 without changing a thing, than go back up to 10.1 and back and forth in-between.

 Pascal

 

 --

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Tue Oct 29, 2013 2:03 pm Post subject: Re: Fuel Pump Issue

I spoke to a couple of vendors and my A&P of choice yesterday. The consensus was to:



* Revisit sensor settings and connections (I don't expect this one to reveal much)



* Closely examine the fuel system for anything obvious.



* Replace the Tempest Fuel Pump with a (new, not rebuilt) genuine Lycoming Pump



18 psi is definitely not acceptable. Van's had no input (guess who sold me the fuel pump). They claimed they'd never heard of such a thing and were out of touch (their words) with builders. Really? If so, that's disturbing on several levels.



This particular component is too darn critical to screw around with. It needs to work and be a known quantity.



Jay

433RV - flying

rleffler

Joined: 05 Nov 2006
Posts: 680

Posted: Tue Oct 29, 2013 3:19 pm Post subject: Fuel Pump Issue

I did simulated take offs at altitude with the boost pump off.  My fuel pump

was rock steady at 22-23 psi.   I still don't know if  the pump replacement

or the cooling shroud was the solution.



bob



--

_________________
Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Tue Oct 29, 2013 4:35 pm Post subject: Fuel Pump Issue

Well, the Lycoming pump had an AD on it, as did the AC pump that it was 

copied from. I don't recall there being one on Tempest.

I've been flying behind an overhauled AC pump for about 14 years with no 

problem at all, roughly 650 hours.

If those recommending new Lycoming are involved in the procurement in 

any way, I'd disregard the advice. The pump is one of the easiest 

devices out there to overhaul, mostly replace two diaphragms.  Talk to 

Tempest about it, they might be interested, as they are generally one of 

the more reputable parts vendors.

Kelly

A&P/IA

On 10/29/2013 3:03 PM, hotwheels wrote:

 	  Quote: 	
		   



 I spoke to a couple of vendors and my A&P of choice yesterday. The consensus was to:



 * Revisit sensor settings and connections (I don't expect this one to reveal much)



 * Closely examine the fuel system for anything obvious.



 * Replace the Tempest Fuel Pump with a (new, not rebuilt) genuine Lycoming Pump



 18 psi is definitely not acceptable. Van's had no input (guess who sold me the fuel pump). They claimed they'd never heard of such a thing and were out of touch (their words) with builders. Really? If so, that's disturbing on several levels.



 This particular component is too darn critical to screw around with. It needs to work and be a known quantity.



 Jay

 433RV - flying





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=411712#411712

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Tue Dec 17, 2013 5:53 pm Post subject: Re: Fuel Pump Issue

Update on my fuel pump issue... I replaced the suspect Tempest fuel with a new Lycoming pump and no longer have any engine stumble issues. The fuel pressure now consistently displays ~20psi. No more stumbles when switching tanks or at high angles of attack. I just finished up my annual and closely examined the entire fuel system for any blockages... Nothing was found in any screen. I also opted to leave my Flowscan sensor in the tunnel as it's not broke, so there's nothing to fix.



Cheers,

Jay

N433RV - Flying



[quote="hotwheels"]I spoke to a couple of vendors and my A&P of choice yesterday. The consensus was to:



* Revisit sensor settings and connections (I don't expect this one to reveal much)



* Closely examine the fuel system for anything obvious.



* Replace the Tempest Fuel Pump with a (new, not rebuilt) genuine Lycoming Pump



18 psi is definitely not acceptable. Van's had no input (guess who sold me the fuel pump). They claimed they'd never heard of such a thing and were out of touch (their words) with builders. Really? If so, that's disturbing on several levels.



This particular component is too darn critical to screw around with. It needs to work and be a known quantity.



Jay

433RV - flying[/quote]

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