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Ace Hobby . Esprit Model . Thunder Power RC

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Gasser Model RC Helicopters > Zenoah and return fuel line
 
 
Arthur Dent
Heliman
Location: Finland

My Posts This: Topic  Forum		We have Zenoah 3D-Max and question is that is it normal when you start your engine and let it idle, there is not coming fuel from return fuel line to tank.

If you start add more throttle and pass about 20% throttle,then there is coming lot of fuel to tank and tank is like foaming?

Is there something wrong?

AD
11-07-2009 08:09 AM
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shawmcky
Key Veteran
Location: Isle of Wight,United Kingdom

My Posts This: Topic  Forum		Sounds like it is possible

you are sucking air and blowing bubbles in the tank,be worth checking the in tank pipe and pick up and other lines to the carb.If you have an inline filter best do away with it and use a good in tank filter such as the walbro type.Check the flapper valve diaphragm has not gone hard if old as well.Make sure the carb gaskets are good and the small pulse port holes are lined up on the gaskets and fittings and the carb is secure.Throw in a gentle carb clean as well for good measure.

Team- unbiased opinion,no experts here just trying to help thats all.K.I.S.S principle upheld here
11-07-2009 10:10 AM
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Arthur Dent
Heliman
Location: Finland

My Posts This: Topic  Forum		We checked the fuel lines and there were no leaks.
Also we have another engine with 643 carb and we changed it to engine and it is doing same thing.
What should we do next?

AD
11-15-2009 03:00 PM
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ddavison
Veteran
Location: Brownsville, Pennsylvania

My Posts This: Topic  Forum		Foaming is usually a sign of vibration. Check your fan balance and runout. Check your engine alignment to the clutch. Also check the pinion to main gear gap.

DaveDavison, Miniature Aircraft Field Rep. Spectra,Stratus,Furion, JR 12x 2,4
11-15-2009 04:30 PM
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AceBird
Elite Veteran
Location: Utica, NY USA

My Posts This: Topic  Forum
Quote 
Is there something wrong?

I would say there is. There shouldn't be any fuel moving through the return line except when you squeeze the bulb on the carb. Fuel foaming does indicate vibration so maybe the vibration is causing the other problem. Hard to tell from here.

Ace
What could be more fun?
11-15-2009 11:20 PM
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Arthur Dent
Heliman
Location: Finland

My Posts This: Topic  Forum		I understand the foaming if it's comes from vibration.
But what could be wrong if the carb will bypass the fuel back to tank?

At idle, there is not coming any fuel, but after we increase throttle, then it start to flow plenty to tank.

We have tryed another carb with same thing. Could it be the muffler the reason? It's only thing which is same with both test.

AD
11-16-2009 07:36 PM
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Chris Bergen
Elite Veteran
Location: location

My Posts This: Topic  Forum		Let me ask this,

How is the engine running?

Besides vibrations, which may be related to tuning, oil mixture, or fan not indicated, how does the engine RUN?

Chris Bergen
11-16-2009 07:57 PM
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Arthur Dent
Heliman
Location: Finland

My Posts This: Topic  Forum		Hi and thanks replying,

Engine will start and it will idle and if added throttle it will take rpm's.
But it seems to be little rich cause there is coming little oil drops from pipe.

We have indicated the fan assembly and have eliminated almost all vibrations so otherwise heli should be ok.

Only odd thing is that fuel is coming back to tank from the carb. And if we add more throttle, more fuel is coming to tank and then fuel is like foaming inside the tank. If you lower throttle and go to idle, then there is not any flow to tank.

I have the information that there should not be any fuel flow back to tank, but why we have. Is it normal or should we just let it be or what could we do?

Thanks!

AD
11-16-2009 11:07 PM
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Excalibur
Veteran
Location: Destination: Earth

My Posts This: Topic  Forum		Hi AD:

I'm trying to figure out how you can see (interpret) fuel flowing from the carb to the tank through the return line.

How can you see this when throttling up if you are a safe distance away from the heli? Can you actually SEE fuel squirting back into the tank from the return line? The tank is translucent and very difficult to see into.

Don't go just by the fuel foaming in the tank, that's vibration, plain and simple. Could you please explain this in a little more detail? It just doesn't make sense. . .

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
11-17-2009 05:21 AM
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Arthur Dent
Heliman
Location: Finland

My Posts This: Topic  Forum		Yes it's fuel or air coming back.
It can been seen before heli start hover.
And when it's hovering, then it can been seen little far away.
It have to be fuel or air.

There is like little storm inside the tank and it's coming from the return line nipple. Went so close that it can be seen.

That's why this whole thing is so odd.
My friend have a RC plane with Zenoah and he told me also that there should not be any flow back to tank, but he hasn't any answers why our engine is doing this.

We have 3D max and 3D Pro engines. We changed the carb from 3D Pro to 3D max and same thing. The engine and muffler are only the same parts at heli.

Could the reason be muffler if it's broken and it gives some kind of back pressure or something to engine? The muffler is Tornado V3. Before we started to use Tornado we had Zimmermann at place and I trued to remember that with Zimmermann, there weren't happening this.

I have to test it again. But if someone have explanation, please let me know.

AD
11-17-2009 06:01 AM
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Fixit
Elite Veteran
Location: UK

My Posts This: Topic  Forum		I had this miss conception and thought the foaming was caused by the return pipe until I read a thread about running the return pipe under the heli and not into the tank, it will be a good test if you run the return pipe outside and maybe tie wrap it too the base plate and then run the motor up, I’m sure you wont see any fuel coming out but you will still have the foaming in the tank.

I only like to fly gassed up
11-17-2009 11:44 AM
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AceBird
Elite Veteran
Location: Utica, NY USA

My Posts This: Topic  Forum		Are you using a vent line? Three hoses to the tank not just the feed and return. Does the bulb empty?

Ace
What could be more fun?
11-17-2009 02:18 PM
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Mikado Modellhubschrauber . Futaba-RC . Boca Bearings

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Gasser Model RC Helicopters > Zenoah and return fuel line
 
 
Excalibur
Veteran
Location: Destination: Earth

My Posts This: Topic  Forum
Quote 
it will be a good test if you run the return pipe outside and maybe tie wrap it too the base plate and then run the motor up

THAT would be a definitive test. If you truly do have fuel coming back out the return line you would see it squirting out onto the ground when you rev up the throttle. Please try this and post your results.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
11-18-2009 05:26 AM
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Ace Hobby . Esprit Model . Thunder Power RC

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Gasser Model RC Helicopters > Zenoah and return fuel line
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