Return line in perry pump
 

Hello
I've had a nightmare setting my webra 1.20 with perry pump
To make story short after wasting many weekends and no flying I installed the attached return line to avoid excess fule in my carb, then the engine in idle mid range and full throttle was running beutifully.
With the nose up the engine was too lean and did not get enough fuel , regardless how open did I have the High speed needle valve.
Then I quit and returned to the original set (no return line) and used a perry carburator, same excess fuel , I have no idle at all with all idle disc closed , i had to guess 'cause the idle disc does not have an end.
Is there anything wrong with my return line?
I forgot to say That I fill the tank through the clunk by unpugging the filter so I would prefer keep it as a two way tank
I've seen many diagrams , I notice that inb some cases the fuel returns to the fuel line and in my case it returns to the tank, could that be the difference? and I don't see whay in my case the engine would run lean but IT DID so I would take any advice so I can sleep:)
Regards and thanks in advance
Sorry for my sketching I always sucked in drawing
Omar

RE: Return line in perry pump
 

There are probably lots of people who know better than I and I have never used a Webra engine but I have used Perry pumps on OS engines for 1000's of flights and have never had a problem of any kind. I also have never heard of using a return line. If I had to do something like that I would get rid of the pump or the engine.

RE: Return line in perry pump
 

Omar,


There are a few guidelines for such an installation:

1. The fuel line between the T-junction and the carburettor must be short; less than 1".

2. The second T-junction should be used (placed in the fuel-line before the pump), or a nose-up attitude may empty the return line faster than the pump can refill it.

3. The pump has an adjustment screw that allows you to increase, or decrease the flow. Use it.

4. The fuel in the end of the line is fed to the engine by carburettor pressure depression only. Such a setup will not work with a non-suction carburettor, like the Perry pump carburettor (or a Webra Dynamix...). If your engine originally came with the Perry pump, it will not function properly with the return line setup.


I believe '4' is the problem you are encountering, but you know better.

RE: Return line in perry pump
 

Dar
Thanks for the tip
It sounds like my problem is in the second point, maybe the line gets emptied faster than the pump rreplaces it
About the carburator, I have the TNII like tyhe one in the picture I think those work with pressure depressure
ANyway I'll make sure I put all your feedback in my plane and see if it works.
About the other repply, I must mentioin that idle in O.S Carburators has more room to go than in webra.
Regards
Omar

RE: Return line in perry pump
 

I think I forgot to add the carb's picture link
http://www.webra-austria.at/motor.ph...RETTOR&lang=EN
Regards
Omar

RE: Return line in perry pump
 

I second Dars post. I suspect there is a quality control problem with recent Perry Pumps which affects the pump regulator. You should be able to get more fuel to the carb by using a smaller fuel line. You could also put a remote needle in the return line. If you do you would turn the needle in to make the mixture richer.

Perry makes a remote needle as well as others. Perry or some body once made an adjustable clamp that went over the return line and turning the screw would squeeze the line and restrict the return flow.

RE: Return line in perry pump
 

Omar,


The normal TNII carburettor can function on venturi suction alone (exhaust pressure is recommended).

...But since it came on an engine originally equipped with a high pressure fuel delivery system, maybe it is not a 'normal' TNII...

If you go through the check-list, you will find and overcome your problem.


In any case, with the Perry pump, you must never use exhaust pressure.
The tank's 'pressure' tube must remain vented to atmospheric pressure.

RE: Return line in perry pump
 

Can someone please explain why you need this return line ? As I stated above I have been using Perry pumps for over 15 years and have never needed a return line and until now have never even heard of such a thing. I'm just curious and willing to store some new info.

RE: Return line in perry pump
 

Thanks for the info
The engine came without pump, I just added since I have the tank in the CG so muffler pressure won't be enough to get the engine running wel.
The vent line of my tank is free into the atmosphere.
I just read a post lastnight and saw some diagrams and tried to give them a shot
regards

RE: Return line in perry pump
 

Don M
The thing is that even with all the idle needle screwed in I don't have idle which means the pump is flooding the engine
I have unscrewed the pump regulator screw and no effects
I have used Perry carburator, no success
The engine still gets flooded in idle and midrange and I repeat I have all the idler bar closed
I also have used perry in O.s 91 fx with no problems, OS carburators seem to have better idle set up, in webra I went all the way and still it's too open
Regards

RE: Return line in perry pump
 

You said it was running fine with the return, except when the nose if pointed straight up. Seems to me you are almost there, either set the needle richer so it will work with the nose up and settle on running richer when level, or do something to help get fuel to the carb. Either place the tee closer to the carb as Dar suggested, or use a smaller or restricted return line, either one of these could do the trick. As Dar said the Perry pump carb needs regulated pressure, and your pump was not doing this. For the price of the Perry pump carb you could have bought another Perry pump which works. Did you ever try to exchange the pump for one that works?

RE: Return line in perry pump
 

Omar,


Find that other T-fitting that came with your Perry pump and install it in the fuel-line, between the tank and the pump.
Connect the return fuel-line to it and plug that now redundant tube in the tank.

Please follow [link=http://www.perrypumps.com/Pump%20and%20Bypass%20System.pdf]this Perry document[/link] to do it right.

RE: Return line in perry pump
 

Thanks for the info
I already replaced the pump for a new one, same thing
In nose up I open the heedle valve and no effects it looks like the fuel prefers always to go by the returns than through the carb as expected.
I put the return now so close tha almost the carb fiting touches the tee so I am still frustrated with that.
I put the additional tee (I tested the engine this morning at home in my fron yard:)) and still the engines gets flooded .
I already ordered a new engine a moki 1.35 and I planning to use it w/o pump, I have wasted a lot of money on getting my biplane flying Ok but I have failed, I have to admit it.
Maybe later down the road I will invest the money in a cline regulator which the people just keep saying it's a marvel.
Regards

RE: Return line in perry pump
 

Are you pulling our leg? You said in an earlier post that the engine ran fine with the return line, except for leaning out with the nose pointed up. Now you say it floods at idle with the return? I'm sorry I do not see how the pump can flood the carb with the return line. Starve with the nose pointed up yes, but no way can it flood a good and well adjusted carb. With the return line in place the pressure to the carb will be exactly that of the resistance in the return line, and we all know that isn't much. Sounds to me like you have a bad carb or pulling our leg.

RE: Return line in perry pump
 

Sport Pilot
A month ago I tries the retrurn and that's where it got lean in nose up.
Then I switched tyo perry carb, nothing to report
This morning I retook the return line thing and added the tee before the pump (before I had the return coming into the tank thru a vent line) and first the engine dis not start, then I opened the needle the engine started atumbling (flooded), then I opened both high speed and idle, the engine was very rich, nose up, then accelerated and lean again.
How come if I have the engine very rich horizontal with a lot of smoke thru the mufler and stumbling at full throtle, when in nose up again gets lean?
This morning was my 5th aproach to solve the problem with no success.
The only option I have would be to try the same setp with a perry carb and see what's gonna happoen.
I bought this engine used in RC universe, when got it was totally powerless, I replaced cilinder liner and a ring (80 USD), then I replaced the carb for a perry (30 USD) then I replaced the pump (30).
I am sure there is something wrong with the engine some how
I have the same set for an extra 300 (engine, pump, prop) and altough the engine runs a little rich I still can enjoy it.
After 4 months of trying to solve the problem I concluded the hobby is not to be tuning engines, I need to fly!, that's why I told to myself I have enough and got a new engine(moki 1.35), If I still keep the tank at the CG I'll use a cline regulator instead.
Gary conley from perry has told me several times that I should thinkl simple that perry has been in the business for a while.
Maybe I was cursed and got the things not working or maybe is the engine
Regards

RE: Return line in perry pump
 

Sounds like to me the pump simply isn't pumping. Can you see anything comming from the return?