Air Bubbles in Fuel Tank?

I have a new os .75 AX.
I have constant air bubbles in the fuel line.
I have checked air lines and tank and everything looks good as far as I can tell.

There seems to be allot of blow back from the exhaust creating violent agitation in the fuel tank.

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Bubbles
by: Anonymous

Engine too lean? That might also cause bubbles.

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?
by: Tom

Does the bubbles go away when you remove the vent line from the exhaust?

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Air bubbles
by: Anonymous

Everything is good when removing the return line to the exhaust.

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Angled exhaust tube?
by: Matt

Is the exhaust line inside of the tank pointed upwards like the picture below?



Make sure this line is angle upwards and touches the top of the tank. If this line gets submerged you will get tons of bubbles.

Engine vibration is another source of bubbles. Make sure your prop is balanced and all the mounting bolts are tight.

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Bubbler
by: Anonymous

You're running way too lean. Cut that out asap!

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Having the same problem
by: Chris

At full rpm the engine starts to struggle and leans out - I have to really richen it up to keep it running. The tank seems to have a lot of blow back (pipe is pointing up).

Only thing is it is an ARTF so the tank hasn't got any rubber or foam around it so could be causing bubbles.

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