Using check valve in YS 140DZ fuel system

[Earl Haury]

Peter, et al

Guys - forget the paragraph regarding the check valve in the feed line. I 
must have been in the sun too much at the Nederland contest over the 
weekend. There is no obvious value to a YS check valve in the feed line. 
Obviously, if install to block tank pressure flow - no fuel could flow to 
the engine. I guess I could say that I was checking to see if anyone was 
paying attention?

The inlet line stuff is valid and been used successfully.

Earl
----- Original Message ----- 
From: "Peter Pennisi" <pentagon.systems at bigpond.com>
To: <discussion at nsrca.org>
Sent: Monday, August 30, 2004 5:39 PM
Subject: RE: Using check valve in YS 140DZ fuel system


>
>
> Hi Earl,
>
> Are you saying in your first paragraph that the fuel head pressure and
> pressure caused by thermal expansion is lower than the pressure required
> forcing the check valve to open and allow fuel to flow?
>
>
> Peter
>
> Peter Pennisi
> Pentagon Systems QLD Pty Ltd
> P.O Box 4280
> Eight Mile Plains
> QLD 4113
> Australia
> Phone:    61+0738414234
> Fax:        61+0738414264
> Mobile:   0408007206
> Email: pentagon.systems at bigpond.com
>
> -----Original Message-----
> From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] 
> On
> Behalf Of Earl Haury
> Sent: Tuesday, 31 August 2004 8:22 AM
> To: discussion at nsrca.org
> Subject: Re: Using check valve in YS 140DZ fuel system
>
> Peter
>
> You're correct regarding check valve placements regarding fuel / air flow.
> The pump inlet valve will unseat with very little positive pressure, if 
> the
> carb is even slightly open, fuel will then flow into the head via the
> injection path and flood the engine. The intent of the check valve in the
> feed line is to prevent fuel tank head pressure, thermal expansion 
> pressure,
>
> or fueling pressure from causing fuel to flow to the engine when it's not
> running, thereby causing flooding (eliminates the need to clamp the fuel
> line).
>
> The pressure drop across the check valve is very low and will not 
> generally
> impede fuel flow unless fuel draw is diminished by a worn pump. However, a
> worn pump will demonstrate other unacceptable symptoms. Notably, loading 
> up
> at idle and leaning on vertical uplines. (Side to side movement of the 
> upper
>
> inlet pushrod in the pump housing is indicative of wear.)
>
> My favorite system is to use the loop vent and an external clamp 
> (available
> from the heli guys) on the feed line. Simple, positive, and effective.
>
> Earl
> ----- Original Message ----- 
> From: "Peter Pennisi" <pentagon.systems at bigpond.com>
> To: <discussion at nsrca.org>
> Sent: Monday, August 30, 2004 4:41 PM
> Subject: RE: Using check valve in YS 140DZ fuel system
>
>
>
>
> Hi Tony,
>
> Could you please share your thoughts on check-valve placement especially 
> on
> the injector line? Earl also suggested placing one on the fuel feed line 
> if
> I understand correctly. That makes it 3 possible locations when you 
> include
> the vent line.
>
> I didn't know that people are placing them in the injector line. I am very
> interested to hear more.
>
> Earl, what is the theory behind placing it on the feed line. I assume in 
> all
> of the cases the valve is orientated such that it goes in the direction of
> either fuel or air flow, or is there something different here as well.
>
> Sorry for all the questions, now you have me thinking.
>
>
> Regards,
>
> Peter
>
>
>
> Peter Pennisi
> Pentagon Systems QLD Pty Ltd
> P.O Box 4280
> Eight Mile Plains
> QLD 4113
> Australia
> Phone: 61+0738414234
> Fax: 61+0738414264
> Mobile: 0408007206
> Email: pentagon.systems at bigpond.com
> ________________________________________
> From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] 
> On
> Behalf Of tony at radiosouthrc.com
> Sent: Tuesday, 31 August 2004 5:25 AM
> To: discussion at nsrca.org
> Subject: Re: Using check valve in YS 140DZ fuel system
>
> Ed:
>
> Most of the uses of the check valve are in the injection line going to the
> head. This will also prevent the line from going empty during idle
> maneuvers, and giving a hesitation during throttle up, like at the bottom 
> of
> an outside loop. I have installed one earlier this year, and it did seem 
> to
> help this issue.
>
>
> Tony Stillman
> Radio South
> 3702 N. Pace Blvd.
> Pensacola, FL 32505
> 1-800-962-7802
> www.radiosouthrc.com
> ----- Original Message ----- 
> From: Ed Deaver
> To: discussion at nsrca.org
> Sent: Monday, August 30, 2004 2:06 PM
> Subject: Re: Using check valve in YS 140DZ fuel system
>
> I've used the check valve in the vent line from day one without any
> problems. Have never noticed any pressure buildup at all in the tank.
>
> ed
>
> Peter Pennisi <pentagon.systems at bigpond.com> wrote:
>
>
> Some flying buddies of mine have been having a discussion about using a
> check-valve in the fuel system to essentially stop fuel from dripping out 
> of
> the vent line. I have been using this system without any problems that I
> know off for some time. One of the pattern flyers I fly with is very good
> with engines and he doesn't think it is a very good idea to use the valve 
> in
> the DZ fuel system as the tank will always have a slight pressure build up
> inside which may result in inconsistent engine runs. I don't know about 
> his
> theory but I do know that all the Japanese flyers at the recent CAOCC 
> event
> were using check valves in the fuel system.
>
> I would be interested to hear from anyone who may have an opinion on this
> subject.
>
>
> Regards,
>
> Peter
>
>
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