SonexBuilders.net

Installed an Air Ward burp tube kit on Aero-Vee/Aero injector equipped 0nex 74 210 hrs ago never had a problem.
Tom Ryan..........0nex 74

Where can I buy a burp tube?

Gary-sonex 1599 gary49855@gmail.com

Most are custom made from fittings out of the wicks or spruce catalog. Airwad.com sells a kit but for the $300 they want you would be better off buying a different carb that doesn't make the engine stumble in the first place.

Keith
#554

This is Merle Reppert---I am the guy that came up with what I called --BURP TUBE--------------
All you need is a T fitting Where the fuel goes in the TBI---With the SIDE OUTLET POINTING UP---Run a
fuel line from there up to the Vent fitting at the filler neck -----The fuel Vapors ( Over heated fuel that vaporizes
from heat ) will rise up the BURP TUBE and condense where it is cooler before it gets to the tank vent---
This tube is always full of fuel at the same level as the tank--It is that simple---If you are Taxing and are real
hot ----Low fuel flow --and hot Carb you could still get a Burp---Insulate the fittings at the Carb and lines Regular Carbs have a float bowl that vent the vapors----

Got mine from Air Ward 225 hrs ago.. Aero-Vee 2180 with aero injector.. Works great, Have never had a problem.
Tom Ryan...........0nex 74

If all the components of the fuel system are pointed down hill from the fuel tank to the AeroVee then the burp tube is redundant. I removed the gascolator and made sure the aeroinjector was the low point in the fuel path and have never had a burp since. I think the burp tube is benign at best and another single point of failure at worst. YMMV

wlarson861 wrote:If all the components of the fuel system are pointed down hill from the fuel tank to the AeroVee then the burp tube is redundant. I removed the gascolator and made sure the aeroinjector was the low point in the fuel path and have never had a burp since. I think the burp tube is benign at best and another single point of failure at worst. YMMV

Fuel line pointed down hill from tank while on ground would do same as a burp tube, but Is fuel line still pointed down hill when is a long climb? Perhaps, your Sonex with an AeroVee does not climb at high enough angle to reverse that, but mine with a 3300 sure does. Acceleration also pushes fuel pack towards tank, and any air in the line forward

David A.

wlarson861 wrote:If all the components of the fuel system are pointed down hill from the fuel tank to the AeroVee then the burp tube is redundant. I removed the gascolator and made sure the aeroinjector was the low point in the fuel path and have never had a burp since. I think the burp tube is benign at best and another single point of failure at worst. YMMV

Good point. Some have blamed the gascolator as the culprit, but perhaps its just the low position of it on the plans.
If the fuel vaporizes downstream of the gascolator, the bubbles have no place to go besides through the aerocarb, causing burps. If its downhill from the tank to the carb at a three point stance, the bubbles simply go back up to the tank and never reach the carb. The burp tube gives some of the bubbles a place to go.
Mine is as plans, using the gascolator as the firewall pass through at the bottom of the wall then route the fuel line up to the carb. If I did a straight shot from the tank, through the wall and to the carb, it probably would eliminate the need for burp tube.

DCASonex wrote:

wlarson861 wrote:If all the components of the fuel system are pointed down hill from the fuel tank to the AeroVee then the burp tube is redundant. I removed the gascolator and made sure the aeroinjector was the low point in the fuel path and have never had a burp since. I think the burp tube is benign at best and another single point of failure at worst. YMMV

Fuel line pointed down hill from tank while on ground would do same as a burp tube, but Is fuel line still pointed down hill when is a long climb? Perhaps, your Sonex with an AeroVee does not climb at high enough angle to reverse that, but mine with a 3300 sure does. Acceleration also pushes fuel pack towards tank, and any air in the line forward

David A.

The airplane has been a turbo for the last 100 plus hours which does have a higher angle of attack than before. I just changed to a Jabiru 3300 and have the same fuel path as the AeroVee. I only have 4 hours on the new engine but not one burp. N861SX is a tail dragger and the fuel path is sloped downward when it is on the ground so even more steep when in level flight. All the testing so far has been in ambient temperatures above 90 on the ground. I have not wrapped the exhaust yet nor insulated the fuel line, so far no burps.

Bill,

You may have found something, that if you can keep air or vapor from forming in line when on the ground at low RPM and flow rate, the higher flow rate might keep vapor from forming at higher power settings. Hope your 3300 works well. They are a blast to fly in in a Sonex. Is yours one of the new aluminum cylinder series or a previous version ?

David A.