Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Aux fuel pump in 701

Matronics Email Lists Forum Index -> Zenith-List

View previous topic :: View next topic

Author Message

george.mueller(at)aurora.
Guest

Posted: Tue Feb 21, 2006 10:04 am Post subject: Aux fuel pump in 701

I am thinking about the fuel system in my 701 and am considering putting in

a facet fuel pump as a booster pump  The pump I am considering is an

FP40105 which doesn't have a check valve and puts out 25 to 45 PSI (my

understanding is the Rotax 912 can handle a max pressure of 58psi)  This

pump would be used to avoid vapor lock on take off and as an aux pump if

the mechanical pump on the Rotax fails  I would install the pump after the

gascolator and after an in line fuel filter, basically next to the

gascolator  Are there any problems that anyone can see with such an

installation?  I am concerned with the greater likelihood of vapor lock

with auto gas





George

frank.hinde(at)hp.com
Guest

Posted: Tue Feb 21, 2006 10:50 am Post subject: Aux fuel pump in 701

Facet fuel pumps are usually plunger types and really do not need a

filter before the pump. Being completely anal about fuel system design

(seen too many vapour lock occurances) I like to have NO possible

restrictions between the tank and pump and put the pump at the tank.



With a high wing plane you could also put it down low.



I would install it before the gascolator (Gascolators have been known to

leak air which could conceivably air lock your pump...Almost as bad a s

VL). The gasolator works just fine on my 601 in this postion.



The pump pressure sounds awfully high. The Stratus uses the same carbs

as the Rotax and works perfectly well with a 40106 (40105 will show zero

pressure at full throttle and a single pump operating...so go for the

106). I would be concerned about the high pressure pump overcoming the

needle valves in the carbs.



How will you plumb the electric pump relative to the engine (YUUCK!...I

would delete the mechanical pump and run two electrics) pump?...Series

or parallel?



If in series are you sure there is not a failure mode in the mechancial

pump where the electric pump will do you no good?



Safer way is in parallel with a check valve around the mechanical pump. 



You will probably need  a check valve around the electric pump with this

installation too in case it fails ( unless the mechanical pump can

easily suck thru the dead electric pump)...Assuming you mechanical pump

won't vapour lock at the same time.



In fairness, I have never heard of anyone having a problem with a Rotax

mechanical pump even on low wing aircraft...As I said I am anal.



Use 3/8ths lines between the tanks and inlets to the pump...1/4 on the

pessure side is fine.



Frank



601HDS 2* electric pumps (no mech pump) 400 hours

RV7A injected 2* electric pumps (n mech pump)...Hope it works..



--

frank.hinde(at)hp.com
Guest

Posted: Tue Feb 21, 2006 11:03 am Post subject: Aux fuel pump in 701

Ok re-read this...You are considering a 40105...Thats 2.5 to 4.5psi

probably...Yeah its probably OK on a high wing.



Depends also on how you intend to plumb it...if in series the pressure

will be cumulative (unless there is som kind of pressure relief) This

may well put over the pressure acceptable at the carb.



If in parallel..it might still be better with the 105 as you will gain

roughly 1 psi for 4 feet of elevation gain between the pump inlet and

the tank. This will put your 105 pump in the 3.5 to 5.5 psi range for a

4' elevation. Its probably OK for a no mechanical pump operation in

parallel.



(remember if in series to account for the ressure drop of a dead pump,

if it will even work at all.



Have fun..



Frank



--

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Tue Feb 21, 2006 11:03 am Post subject: Aux fuel pump in 701

I think your numbers are off by a factor of ten. 2.5 to 4.5 psi sounds about

right for the fp40105.



If your fuel is in wing tanks, you probably won't need a booster pump

because the high wing 701 will gravity feed the fuel to the engine. But, if

you are going to put a pump in your system, it should go before the filter.

The fuel filter should be the last thing in the fuel line before the

carburetors. A clean filter might not cause a problem but if it starts to

clog up it will cause a flow restriction and the pressure will drop as fuel

flows through it. A pump can push fuel through a partially clogged filter

much better than it can suck fuel through it. Drawing suction on a fuel line

is a real good way to cause vapor lock. The lower the pressure, the lower

the boiling point. Even cars don't have filters installed ahead of the fuel

pump, just a screen in the tank to keep out larger particles that might

interfere with the pump.



This subject has been covered many times in the past on this list. You can

check the archives for previous posts on this subject.

-- 

Bryan Martin

N61BM, CH 601 XL, Stratus Subaru.

on 2/21/06 12:56 PM, george.mueller(at)aurora.org at george.mueller(at)aurora.org

wrote:



 	  Quote: 	
		   

 

 

 

 I am thinking about the fuel system in my 701 and am considering putting in

 a facet fuel pump as a booster pump  The pump I am considering is an

 FP40105 which doesn't have a check valve and puts out 25 to 45 PSI (my

 understanding is the Rotax 912 can handle a max pressure of 58psi)  This

 pump would be used to avoid vapor lock on take off and as an aux pump if

 the mechanical pump on the Rotax fails  I would install the pump after the

 gascolator and after an in line fuel filter, basically next to the

 gascolator  Are there any problems that anyone can see with such an

 installation?  I am concerned with the greater likelihood of vapor lock

 with auto gas

 

 

 George

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

larry(at)macsmachine.com
Guest

Posted: Tue Feb 21, 2006 12:31 pm Post subject: Aux fuel pump in 701

George,

I've been using a pair of 105s on my HDS and they are both after the 

gascolator and before the

replaceable paper filter.  From the filter to a T, the line branches to 

the Bings.  Works well, but I'd question

putting an annually replaceable filter before the pumps.



Larry McFarland - 601HDS at www.macsmachine.com

do not archive



george.mueller(at)aurora.org wrote:



 	  Quote: 	
		  



I am thinking about the fuel system in my 701 and am considering putting in

a facet fuel pump as a booster pump  The pump I am considering is an

FP40105 which doesn't have a check valve and puts out 25 to 45 PSI (my

understanding is the Rotax 912 can handle a max pressure of 58psi)  This

pump would be used to avoid vapor lock on take off and as an aux pump if

the mechanical pump on the Rotax fails  I would install the pump after the

gascolator and after an in line fuel filter, basically next to the

gascolator  Are there any problems that anyone can see with such an

installation?  I am concerned with the greater likelihood of vapor lock

with auto gas





George

planejim(at)bellsouth.net
Guest

Posted: Thu Feb 23, 2006 7:00 am Post subject: Aux fuel pump in 701

George,



I have 601Hd fuel system plumbed as you described. I use auto gas 

exclusively. It has worked fine for 9 years (500.3 hours). I use the 

electric pump for T/O and landing (in case of a go around) in case the 

mechanical pump dies at the wrong time. The only question I have is the 

pressure you mentioned. My engine driven (Rotax 912UL)  pump and the 

electric pump both put out around 5 Psi NOT 25 to 45 psi as you mentioned. 

My elec. pump is a Facet and I don't use a "check valve" in the system. I 

just checked my purchase records but the receipt doesn't mention the part 

number and the airplane is miles from home. I plumbed the electric pump in 

"parrallel" with the engine pump and it works fine.



Good luck.



Jim Hoak 601HD 500.3 hrs.

---

Larry Martin

Joined: 10 Jan 2006
Posts: 31
Location: Cabot, Arkansas

Posted: Thu Feb 23, 2006 7:24 am Post subject: Aux fuel pump in 701

If you have a gravity feed system, a carbed engine, and no mechanical pump 

then you should have an aux electric pump, no more than 6 psi to use for T/O 

and other climbs.   It is entirely possible that your carb bowl which is 

normally pretty small can get higher that your tank.  Thus no more gas 

unless you pump it.   I'm talking high wing.  I intend to run a primary pump 

all the time with a second backup aux pump.  It's just something else not to 

have to remember to turn on and off.   And in the remote event the primary 

pump fails, the pressure gauge will fall off but it will still gravity feed 

thru the pump.  I can switch on the aux pump if needed.

Larry, N1345L, www.skyhawg.com

---

_________________
701 with a Harley, www.skyhawg.com

frank.hinde(at)hp.com
Guest

Posted: Thu Feb 23, 2006 7:26 am Post subject: Aux fuel pump in 701

I'm sure it does but what are the failure modes of this set up?



Is there something that could happen to the mechanical pump that

prevents the Facet from being a reliable backup?.... If the pump

diaphram were to rupture would it allow the fuel to backflow (either

back into the tank or inside the cowl)? I don't know the answer to these

questions but you can't simply write off the issue as "works fine" until

you understand how each component might fail and affect the system

performance.



Taking my scenario above for instance, a failed mechanical pump would

not only allow the engine to quit, it could also be a very big fire

hazard!



For us to recommend this setup we need to know a little more I think



Frank  



--

frank.hinde(at)hp.com
Guest

Posted: Thu Feb 23, 2006 7:47 am Post subject: Aux fuel pump in 701

That's a wild looking cowling on that 701...Looks cool!



Not so sure I like the idea of your single pump...Do you know for sure

that you will get full fuel flow through a dead Facet fuel  pump?



Why not simply run two of them in parallel. You can leave them running

all the time or turn both of them on just for TO and landing. A  pair of

40105 Facets in parallel will not jack the fuel pressure any higher than

a single pump and I think there will be enough flow from each pump to

overcome the backflow thru the dead pump...If not you could always put

two check valves in or buy the pump with check valves...(model number

escapes me at present)



Nice plane!



Frank



--

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Thu Feb 23, 2006 12:33 pm Post subject: Aux fuel pump in 701

I have two Facet FP40105 pumps in parallel in my Zodiac. I only run one at a

time and have no check valves. I have never had a problem with back flow

through the inoperative pump. These pumps are designed to allow some back

flow in order to allow the line downstream of the pump to depressurize after

shut down. This back flow is just a trickle which makes check valves

unnecessary.

-- 

Bryan Martin

N61BM, CH 601 XL, Stratus Subaru.

on 2/23/06 10:43 AM, Hinde, Frank George (Corvallis) at frank.hinde(at)hp.com

wrote:



 	  Quote: 	
		   

 <frank.hinde(at)hp.com>

 

 That's a wild looking cowling on that 701...Looks cool!

 

 Not so sure I like the idea of your single pump...Do you know for sure

 that you will get full fuel flow through a dead Facet fuel  pump?

 

 Why not simply run two of them in parallel. You can leave them running

 all the time or turn both of them on just for TO and landing. A  pair of

 40105 Facets in parallel will not jack the fuel pressure any higher than

 a single pump and I think there will be enough flow from each pump to

 overcome the backflow thru the dead pump...If not you could always put

 two check valves in or buy the pump with check valves...(model number

 escapes me at present)

 

 Nice plane!

 

 Frank

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

tshank(at)megsinet.net
Guest

Posted: Thu Feb 23, 2006 4:37 pm Post subject: Aux fuel pump in 701

I don't think anyone has adequately explained the difference between the 

mechanical engine pumps and the electric. The electric pumps typically 

have an oscillating plunger that pumps the fuel though a pair of check 

valves giving a rated pressure. If it is for example 5 psi then two 

electric  pumps in series is 10 psi. The engine pump operates 

differently when the lever that is driven by an engine cam is moved it 

pulls the diaphragm such as to enlarge the pumping chamber. This action 

is against a spring. This is the intake stroke for the pump that pulls 

fuel into the pump chamber. The fuel is forced out of the chamber by the 

spring pressure and not the return of the pump lever which is connected 

by a mechanism that does not allow it to pump on the return stroke. In 

that way the spring determines the pressure of the pump not the engine 

speed. In like manner if the fuel is being fed to the pump under 

pressure the mechanical pump is not additive. The is the output pressure 

will be which ever is higher the electric pump or the mechanical pump. 

This is why for years certified low wing aircraft have had a mechanical 

engine pump and a boost pump with no over pressure problem. For my 

installation since I only have electric pumps I connected them in serial 

with a pressure regulator to keep the pressure at 5 psi.



Tim Shankland



Jim Hoak wrote:



[quote]



George,



I have 601Hd fuel system plumbed as you described. I use auto gas 

exclusively. It has worked fine for 9 years (500.3 hours). I use the 

electric pump for T/O and landing (in case of a go around) in case the 

mechanical pump dies at the wrong time. The only question I have is the 

pressure you mentioned. My engine driven (Rotax 912UL)  pump and the 

electric pump both put out around 5 Psi NOT 25 to 45 psi as you mentioned. 

My elec. pump is a Facet and I don't use a "check valve" in the system. I 

just checked my purchase records but the receipt doesn't mention the part 

number and the airplane is miles from home. I plumbed the electric pump in 

"parrallel" with the engine pump and it works fine.



Good luck.



Jim Hoak 601HD 500.3 hrs.

---

craig(at)craigandjean.com
Guest

Posted: Thu Feb 23, 2006 5:23 pm Post subject: Aux fuel pump in 701

Another oft-forgotten point is that there are many models of the Facet

pumps. Some have check-valves, some have anti-siphon valves, some have

neither, some have both. There is a fairly wide variation in the range of

lift, GPH and min/max PSI. In all there are 36 different configurations in

the 12 volt models. The link below is to a PDF (Adobe Acrobat) document on

Facet's web site.



http://www.facet-purolator.com/mcl/media/technology/hd_pdfs/Cubed_Solid.pdf



Or as a tiny URL: http://tinyurl.com/nakhq



-- Craig

vair601(at)yahoo.com
Guest

Posted: Thu Feb 23, 2006 6:12 pm Post subject: Aux fuel pump in 701

Frank,

  If the diaphram were to develop a hole it may exit out the weep hole however it would probably drain into the crankcase as it might still be pumping.  Having a check valve seperating the two pumps, yet a good idea, but not required to have the system function.  After all there is a check valve built into the mechanical pump to begin with or it couldn't pump.  Just my two cents worth.

   

  Bill Jeffries



		

---------------------------------

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum