Jetdesign

My Feedback: (8)

My semi inverted 55AX was spillng fuel out the carb. I was wondering what would cause this, and if it was normal, then i realized i have a one way valve on the pressure line (3 line setup with a 'T' on the exhaust line for cowl use) and that its probably from a buildup of pressure? Am i right or do you think its something else? How would i fix this?

thank you.

Minnreefer

Is this the engine that was on your last plane that you crashed? I assume that it did not get damaged? Did this problem happen before your crash?

Flying freak

all engines that i know of with a carb pointed down will leak a bit when your priming them ....


Steven

RCKen

My Feedback: (9)

GaRCField,
It's normal to have a little bit of fuel leak out of the carb on an inverted engine. But you do need to remove the one-way valve from the exhaust line. You should only use a one-way valve on an engine that is designed to work with that kind of pressure, such as a YS. With it in place your engine is going to leak fuel (such as you described). Remove the one-way valve.

Ken

flyX

I think it that thing call gravity.
You know..thats why there's water towers in cities and towns.

Your still going to get some type leakage.
My instructor had one of those think of ma roo clipped on exhaust line, oneday.
I think it's the same concept as putting your finger over a straw.
How you know why the plumber gose on the roof sometimes instead of looking under the sink.lol

Gray Beard

My Feedback: (-1)

This must mean you found the long lost floater??? See how that works, Never Give Up, Never Surrender!!! {{ Tim Allen}}
That pressure fitting isn't helping any at all, remove it and see what happens. If it is still doing it {A lot} then your tank may be too high and like Fly said, that gravity thing is taking over.
NOw post up and tell us about the joys of finding the long lost plane and the dammage done!!
Inquiring minds want to know!!!

Jetdesign

My Feedback: (8)

The problem definitely is from having the one way valve, but also from me not understanding how to set things up. I had the one way valve between the muffler and the fuel tank, then a 'T' to a line for fuel to drip out when refueling. In my in-expertise I plugged that line too, so the build up of pressure had nowhere to escape. Removing the plug from the extra exhaust line solved the problem, and the one way valve is still working to prevent excess fuel from entering the muffler during refueling.

Ken, on the 3 line system with fuel dots, do you just let the fuel drip out the muffler when you fill?


This was happening before I lost the plane, though I updated the other post - check it out!

RCKen

My Feedback: (9)

GaRCField,
Remove the one way valve from the entire system. On a three line system inside of the cowl simply let the fuel drip out of the muffler. This will let you know when the tank is full. If the muffler is in a position where the fuel would puddle in the muffler then the simplest solution is to put a split in the pressure line from the muffler to the tank, then rejoin it with a piece of brass tubing. Now place this line in a position where you can reach a finger inside of the cowl and pull the line out. Seperate the line when filling the tank and the excess will flow out of the line when the tank is full. Then rejoin the line and tuck it back inside of the cowl.

This is exactly how I set up the Hangar 9 Sundowner that I reviewed - [link]http://www.rcuniverse.com/magazine/article_display.cfm?article_id=929[/link] . Here is a picture that shows what I am talking about that I did on that plane. If you look at the bottom of the plane where the exhaust exits I had to do this. Because of the silicon exhaust extension I couldn't pump until the fuel came out the exhaust. So I did what I just described above. In this picture you can see the blue fuel tubing, this is my muffler vent line. When it's time to fill the plane I just pull this line out of the cowl and seperate it while filling the tank. Then when done I just tuck it back up inside the cowl. Simply, easy, and it works very well.



Ken

Jetdesign

My Feedback: (8)

Thanks Ken, I do have a place to reach in and grab the line. I just realized as I was reading your post that the plugged third line would not allow any pressure to escape the system, and the unplugged third line would allow pressure to escpae between the muffler and the fuel tank.

I'll pull off the valve tonight and re-plumb things.

Thank you so much for your help, it's always appreciated.