dinorc

Hi, my DLE 30 dies in take off; as soon as it picks up speed it dies! It used to work properly until I decided to do a better job with the weights that I installed as far forward under the "box".
Is it possible that they divert the air flow and/or cause turbulence that causes the carb to go waayyy lean?
On the ground it holds max rpm just fine, idle is perfect. On my last attempt I opened the max needle by 1/4 turn...no difference.
The air intake is approx 1/2 inch from the firewall that has a round hole in line with the carb, hole is a little bit larger in diameter than the carb air intake... I will try to buid-up the firewall with some closed cell foam so the carb draws "calm" air from inside the fuselage. Does anybody think it might help?
Any and all advice is very welcome.
Thanks , Dino

playntraffic

this is simple, but maybe you overlooked it. Are all the fuel lines in the tank attached and secure? I had the same problems with my first gas plane. Found that the fuel line had slipped off the barb inside the tank. Good luck.

Mike

dinorc

Hello Mike, thanks for the suggestion, I shall recheck the internal tank fuel lines ( done last week before flying ) even though I do not quite understand why the engine ran perfectly on the ground for quite some time before dying on take off.http://images.rcuniverse.com/forum/micons/m13.gif
I'll let you know what i found.
Dino

dinorc

Hi, checked the fuel tank, unfortunately all fuel lines are in good order. Disassembled the carb, no dirt found, but the diaphragm/needle lever seems to be too low below the carb face. Anybody knows the actual height?
Dino

kmeyers

Installing weights under the box did not bend the needle lever in the carb and neither should you now.

The first guess for disrupted air flow would be that of the cooling air flow (the weights blocked it off ?).

Many people solder a nipple to the pressure regulator hole on the carb and use tubing to route it to a non turbulent area inside the fuse.

Although if you are new to gas simply tunning the engine might be the answer (only a newbie would turn the high speed needle 1/4 a turn, way too much).

A picture of your complete setup would help.and answer a lot of questions.

captinjohn

Photos do help....sometimes a photo is worth a thousand words ! ! ! Capt,

Planejaw

My Feedback: (53)

Dino,

You should have no problem with air draw, but as another response mentioned, photos would be good. Are you using a two or three line setup from your tank? I used to use a two-line setup with a "T" fitting, had a few problems with a couple engines, then went to a three-line arrangement in all of my gassers. Also recently found some dirt in my incoming fuel nipple on the carb. Don't be afraid to pull the carb, clean the screens and blow-out all of the passages and the incoming fuel nipple.

dinorc

Hello, I have solved the problem by letting the carb draw air from inside the fuselage! The photos attached show how simply I did this by using dense foam rubber around the firewall hole.
To answer your questions I use a 2 line from the tank via a Dubro quick fill valve, the carb has been opened again (3rd time) but found no dirt.
I suppose that air incoming from the two top openings of the Sbach 342, not having a clean way out (see photos) towards the bottom opening, blocked by the muffler and the weights underneath the engine box, was rammed into the ventury therefore leaning the fuel mixture enough to stop the engine.
The new set-up also yielded a smoother, lower, more stable idle.

Thanks all for the support.
Dino

Roo Man

My Feedback: (1)

Hello, I have solved the problem by letting the carb draw air from inside the fuselage! The photos attached show how simply I did this by using dense foam rubber around the firewall hole.
[/quote]

Dinorc,

My concern is that the foam is acting as a partial choke and this indicates to me that you may have been too lean on the high speed needle. Did you hold the nose up with full throttle to see if it stalls or looses RPM,s?

Gary

DaveE61

[quote] Hello, I have solved the problem by letting the carb draw air from inside the fuselage! The photos attached show how simply I did this by using dense foam rubber around the firewall hole.
To answer your questions I use a 2 line from the tank via a Dubro quick fill valve, the carb has been opened again (3rd time) but found no dirt.
I suppose that air incoming from the two top openings of the Sbach 342, not having a clean way out (see photos) towards the bottom opening, blocked by the muffler and the weights underneath the engine box, was rammed into the ventury therefore leaning the fuel mixture enough to stop the engine.
The new set-up also yielded a smoother, lower, more stable idle. Hi Dino,

I am just curious if you have done any extended inverted flight? It is possible that there is a float setting problem. If so your engine will quit in a prolonged inverted flight.


Dave