luigi410

This is my Tamiya TG-10 chassis. On the tune pipe there is an outlet which is connected to the top of my fuel tank through a silicone pipe. Now what is this pipe for and what is its name? i put a one way valve between the fuel tank and the tune pipe (dont ask[sm=angry.gif]) and it made my engine difficult to start, and when it did start my exhaust sprayed ALOT of unburnt fuel so i quickly shut it off and removed the valve.
What would happen if i continue to run my model without this pipe?

See the image for a diagram (sorry about the picture quality)

snowbl!nd

The fuel line running from the pipe to the fuel tank is there to provide backpressure (forcing more fuel into the engine as backpressure increases). I suppose you could call it a pressure line.

Do NOT run without it.

Spetz

Yeah it basically makes the fuel tank have pressure and therefore consistent fuel flow into the carb, as there is no pump etc

luigi410

Oh i see. So thats why there was all this loose fuel gushing out of the exhaust without the pipe. Excess fuel was just running past the carb and out!
Thanks for the help guys

snowbl!nd

Excess fuel coming out of the exhaust is unrelated. Without the pressure line the engine should actually run leaner, meaning less fuel would pass through the engine.

ferrarimk13

yes, the fuel meant youre running rich, too much fuel. Never run without the fuel tubing there.

oneofakindtrini

i think it is the back pressure tube.

Philster

The tube pressurizes the gas tank. It helps force fuel into the carb.

Fuel that comes out of the exhaust is from two things. First, two-stroke engines are inefficient and usually waste a fair amount of fuel, since they burn fuel and exhaust gases on the same stroke. This leaves some unburnt fuel and oil to go out the exhaust. Second, running 'rich' is going to provide even more fuel/oil to ensure the engine friction is kept low, and this will mean some goes unburnt.