Burp tubes

[fastj22]

They simply work! My plane has burped when it gets warm on takeoff nearly every flight.
I finally installed the burp tube yesterday and really tested it today. Flew a long x-country for 4.5 hours and two stops and not one single burp. In Dalhart, Texas, it was 91 OAT and the plane heat soaked for a good 30 minutes while I refueled and used the facilities. Fairly long taxi. Normally, I would have expected a series of burps accelerating on takeoff, not a single one.

I use 3/8ths braided hose on AN-6 fittings from the gascolator, through the fuel flow sender to the carb. The burp tube consists of an AN-6 Tee F-M-M simply placed between the supply hose and the carb. Another hose comes out the top of the Tee and is looped up behind the distributors to the top of the cowl. I used a fuel drain valve on the other end of the burp tube. Opening the valve allows fuel to fill the tube to the level in the tank. Then its closed. Any bubbles heading down the fuel line will go up the tube, eventually replacing all the fuel in it. At that point, the burps will return until you refill it by opening the valve. One could route the valve into the fuel fill tray and burp it every time you fill up. Or alternately, just plumb it back to the tank vent leaving out the valve.

For those who can't envision the setup, I'll be happy to take some pictures.

[SvingenB]

I can imagine it works, but wouldn't you get a mega-purp if you have a negative g maneuver and the tube is filled with vapor?

[fastj22]

I can imagine it works, but wouldn't you get a mega-purp if you have a negative g maneuver and the tube is filled with vapor?

A small trade off considering any extended inverted flight will create fuel starvation anyways. And only the bold will go inverted on takeoff, right? :lol:

[flyinbrian]

I would like pictures.
Brian
Waiex N126YX

[fastj22]

I'll take some pictures this weekend and post them.

[merle reppert]

Some comments on the Burp Tube being I came up with it ---It is installed on at least 5 Sonex's in
California with the tube 'T' ed into the tank vent at the firewall---With this setup there is always fuel in
the tube at the same level as the tank--Hot fuel vapor's ( not air ) travel up the tube through the fuel
in the tube and condense from being cooler or exit through the vent line .---No one has burps -----
One guy has capped his tube off at the top -----I prefer it T ed into the tank vent -----This guy
has a lot of hours on it with no problems but only one example ---------All of the installation's
have gascolators--------No more pucker factor ---
Good luck
Merle reppert

[fastj22]

The reason I capped the end was I didn't want it to siphon air into the fuel line at the carb. Probably won't happen, but theoretically it could. I may end up removing the cap and tee'ing it into the vent at the top of the tank too.

[fastj22]

As promised, here's a picture of the setup. the burp tube is the vertical hose. It routes up over the engine and is tied to the oil breather hose so I can burp it when checking the oil.

[XenosPilot]

My Xenos is experiencing the burps lately, as it is heating up in SE New Mexico. I had a bad case of them yesterday at about 99 degF. I have a gascolator as well, and have NO insulation or heat shielding on my fuel line...yet. My exhaust pipes are wrapped in fiberglass, so that helps I'm sure.

My questions are as follows:
(1) Of those who have a burp tube installed, did you also insulate the fuel lines?
(2) If yes above, what did you use? (I'm looking at getting the fiberglass/silicone sleeves)
(3) Did you insulate the gascolator?
(4) Has anyone run into a delayed problem after insulating? I mean, will it still get the burps if remaining hot, but it will take longer to get them...and longer to get rid of them (cool down) as well...also due to the insulation.

Thanks,

[fastj22]

1) yes
2) firesleave
3) no
4) I've only experienced the burps during acceleration down the runway. Once they stop, they stop.