discusmike

My Feedback: (2)

Noticed a air bubble every once in awhile exiting the vent tube,what could be the issue?

discusmike

My Feedback: (2)

Thought it was strange I'm not seeing them in the line that runs to carb

castlebravo

You're probably siphoning some gas out of your vent line. If you fill it until it pours out of the vent and then fly, it will siphon some gas out. You can put an extra loop of fuel tubing in the vent line and this will help. I could show you a video of my Dalton spitting gas out on every downline....and I had a good foot of extra tubing wrapped around my tank. I put in a bit more and this solved the issue.


CB

kmeyers

I'm not sure if I follow, but, if you fill a tank then run an engine. The fuel in the tank is used and air replaces the fuel. The air enters through the vent. I hope this is all we are talking about here.

MTK

If you ever see a bubble in the line that runs to the carb, you will have run problems. That part of the gas feed system must be tight for best results.

On the other hand seeing a bubble on the vent line is not a problem. Typically you may see one when the engine is idling which means it isn't drawing much gas. You should not see one (ground runs only) when the engine is at higher throttle positions. When flying and gyrating, the vent in the tank is gyrating also, meaning the vent inside the tank will be submerged and will tend to syphon gas out. A simple loop of gas line around the tank's neck connected to the vent is all it takes to reduce or eliminate the syphoning.