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  #1  
Old 09-16-2019, 05:45 PM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,128
Default Fuel Filter

Need some advice on where to find an acceptable fuel filter(s) for my new to me RV4. I have an O-360-A1A with a Sensenich prop. I just bought this airplane, and Iím in the initial phases of Ďmaking it mineí. The airplane has two Phenix Industries inline fuel filters (Aircraft Spruce) mounted in the aft end of the center tunnel and angled upwards toward the fuel selector valve. These filters are fairly large - about 6Ē in length and maybe 1.5Ē in diameter, one for each fuel tank. Iím having unusual fuel flow readings from my GRT FF servo, and the fuel pressure also fluctuates some times. I think these rather large diameter fuel filters, mounted the way they are, are cavitating, allowing air to enter the system and collecting in these filters after drainback. Downstream of the filters is the fuel selector valve, electric fuel boost pump, Flo-Scan fuel flow transducer, engine driven fuel pump, and finally the carburetor. I would like to install a couple smaller inline filters in the cabin wells adjacent to the center tunnel, mounted horizontally, which would put them below the normal fuel level in the associated wing tank, one for each tank. I want to get something that is compatible with an aircraft O-360 installation and maybe has a bypass function in case of clogging. I would need a small cleanable filter with cylindrical stainless steel mesh filter that is no more than about 4-5 inches in length so they fit in the side compartments. Any advice, please let me know.

If anyone thinks there may be other issues, please let me know what to look for. Iíve checked all fuel line connections, thinking Iím sucking air from somewhere, but everything seems fine. These filters have not been in the airplane for long.

The airplane is almost 15 years old, has 285 hours on it since new, engine and airframe, and the previous (2nd) owner put 15 hours on it in the one month he owned it. I think he did the fuel filter(s) Ďupgradeí. It runs fine, but the fuel flow has me wondering whatís going on. I can find peak EGT, but the fuel flow might fluctuate from .5 gph (@170 KTS!!) to as much as 13 gph.. fuel pressure sometimes get weird too. Makes me think thereís air in there somewhere, but I might be wrong.

If you can recommend a fuel filter replacement, or anything else, please let me know.

Thanks....
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SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
Cincinnati, OH/KHAO
JAN2019
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  #2  
Old 09-16-2019, 06:03 PM
Darren Kerns Darren Kerns is offline
 
Join Date: Feb 2005
Location: Indiana
Posts: 163
Default

Scott
Congratulations on getting another RV. I am so glad to see you flying again.

Our Fish Fry Fly-in is this Saturday. Try to come over if you can.

Traci and I would love to see you and your wife again!!

Respectfully,
Darren & Traci Kerns
RV7 N599DT
KFRH
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  #3  
Old 09-16-2019, 08:34 PM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 2,191
Default

I use this one.

https://motorsports.flowezyfilters.com/?v=7516fd43adaa

74 micron

Series 3000

it is mounted upstream of the pump and fuel flow meter. fuel flow meter is downstream of the pump.

*******************

I suspect your fuel flow meter for the wacky readings.

I also suspect your airspeed indicator, 170 kts?

It should be 171 kts.
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Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 700+ for all

Simplicity is the art in design.

see Amanda Melton for www.rvplasticparts.com

Last edited by Steve Melton : 09-17-2019 at 05:40 AM.
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  #4  
Old 09-16-2019, 11:13 PM
Bevan Bevan is offline
 
Join Date: Sep 2007
Location: BC
Posts: 1,594
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If you have a look at the size of the hole all the fuel must pass through in the Fuel flow sender, you will understand why it should be downstream of the fuel pump. Sucking fuel through that small orifice is a much bigger problem than sucking fuel through the filters. Vapour lock will show up as loss of fuel pressure between the inlet of the fuel pump and the major restriction. So push fuel through the fuel flow sender rather than suck.

Fuel pumping issues will show up as low fuel pressure and fuel flow irregularities.

Bevan
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O-360-A1F6 (parallel valve) 180HP
Dual P-mags
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  #5  
Old 09-17-2019, 06:01 AM
Red Mtn flyer Red Mtn flyer is offline
 
Join Date: Jul 2017
Location: Carson City, NV
Posts: 78
Default concur

With Steve and Bevan:
A. The unit I used is about the same size as Steve's - getting any smaller for a rebuildable unit with low flow restriction appears to be unobtanium -as is any unit with a 'bypass'.
B. Flow meter needs to be downstream of your mechanical fuel pump, or readings will not be consistent. The flow/ pressure to the carburetor/injection system is what you are looking for - not elsewhere in the system.
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  #6  
Old 09-17-2019, 06:10 AM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,128
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Thanks Steve. I think thatís what I had in my first RV8. It might be a little too long to go where I wanted to put it (them - 2) so I will check. The current filters and whatever I end up with are upstream of the fuel selector, electric fuel pump, and fuel flow transducer on the cold side of the firewall.
Bevan - Not sure how I would mount the fuel flow sender on the hot side, downstream of the engine driven pump in my carbureted engine. Iíll have to look and see if thatís possible, but I think GRT recommends keeping the FloScan on the cool side.
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SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
Cincinnati, OH/KHAO
JAN2019
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  #7  
Old 09-17-2019, 06:23 AM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,128
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Thanks Ben...... apparently it can, and should be put forward of the firewall, and downstream of the mechanical pump. Iím sure thereís a way. Iíll need a new fuel hose setup, which is fine since I was going to replace all the FWF hoses anyway. Good call.
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SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
Cincinnati, OH/KHAO
JAN2019
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  #8  
Old 09-17-2019, 07:06 AM
TS Flightlines TS Flightlines is offline
 
Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 2,338
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Scott----how much room do you have to play with?
Tom
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Joint Venture with Aircraft Specialty
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
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  #9  
Old 09-17-2019, 04:25 PM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,128
Default

Tom,
Not sure yet, Iíll be checking the planned setup soon. Iím currently involved in moving the pilot seat aft about 2.75Ē (big job), which involves several structural considerations. Should be done with that mod by this weekend and then itís on to the fuel delivery setup/changes. Iíll be calling with an order for fuel and oil hoses for my RV4, including the new fuel flow transducer location. Iím sure itís doable - only concern is two more fuel line connections in a hot engine compartment that could possibly leak. But thatís what I did on my fuel injected RV8 and it worked fine.
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SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
Cincinnati, OH/KHAO
JAN2019
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  #10  
Old 09-17-2019, 11:23 PM
Paul 5r4 Paul 5r4 is offline
 
Join Date: Oct 2006
Location: Foley, Al
Posts: 459
Default

Ok, this fuel filter post has me thinking. My 7A has been flying since 2012. I can't remember anything about a fuel filter. Did I miss something. I'll go and have a look at the plane tomorrow. Is this something in the manual? If I don't have one, should I? I understand the purpose and all but can't believe I'd miss something like a fuel filter.
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Foley, Alabama
N729PG..... 450+ hrs
RV 7A, Lycoming 0 320 D1A, Sensenich FP propeller
pilotforfun2001@yahoo.com
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