I use the same, but I shortern the tube by 3/16 every couple of months to ensure a good seal.1/8th I'd tube?

Whew I quite doing that a long time ago. It worked for me for years....right until it did not :-(

I run a belt and braces approach. A positive petcock valve and a luer lock refueling fitting, with a cap over it.

Deleted...

I posted this in the Intairco trap thread...

Mike,
Regarding your MAP trap - I would suggest taking the cap off, remove teflon tape, lightly clean with acetone to get rid of any fuel residue and permanently hysol the cap on. Years ago I had similar issues with an old big can Jetcat P180 using BVM's UAT with enlarged fittings. Was running 3/16" lines, fittings, even dual vents but was still getting air in UAT. During some ground run-ups at high power I finally noticed air was getting thru the UAT cap threads causing the problem due to slight distortion when the nalgene UAT sides sucked in. Gluing the cap on worked, but I eventually switched to JMP's all aluminum unit because that was the only proven option back then. Now we have a wide range of trap manufacturers to choose from and most hard shell ones work perfectly fine.

Make I noticed you said your pump voltage was maxed you check your filters for a clog, I had this same issue just recently and it ended up being a clogged filter due to getting slime growth in my fuel. Just a thought

No no no no no no.
Don't you guys think these things are tested? I know MAP test every BT before they are shipped. I have sold 100's maybe 1000+ and we don't get problems. All you guys are doing is elastoplast other issues. Even with P-200, P-200RX (230+N) and P-220Rxi-B we don't see the plastic bubble traps suck in much. Its all down to the tanks and overflow fittings. We use the Hi-Flow version on anything above a 180 and with any of the Rxi tubines down to the 90. Leave the bubble traps alone, trust the guys putting them together. dismantling them,adding teflon wrap or Hysol glue is just not needed if the tanks are built with the right hardware.
The Nalgon bottle seals on the bottle neck and cap ridge.

If you are still building tanks with 4mm tube or fittings with the same 2.8mm i/d hole-on anything over a 160 you must expect trouble! The Rxi type turbines where Pumps have to Suck, I use 5mm tubes with barbs I had machined. (yes kit/tank manufacturers are slow reacting to the newer turbine demand)

The issues I see at jet meetings here are all with hard walled bubble traps! I have said before, if it was a good idea BVM would have released a Kevlar bubble trap 8 years ago...

Dave, you are 100% correct - issues with the fuel tanks, plumbing or debris in system is normally the problem. However all is can say in that one weird specific problem I had, gluing the cap on the nalgene UAT solved my issues. May have been some small defect on bottle threads, who knows. Prior to that one experience I had used nalgene UAT's on other jet with no issues. I only offered my cap gluing as a suggestion to Mike as something to try.

Thanks guys I thought this thread was dead.

The UAT was sucking in badly until I found the Fuel Restriction in the line. Now Removed, I connect the Data Box of the KT 180 and run pump at full power with the line at the motor going back into my fuel jug, the uat only sucks in a little.

I have already increased the vent line size, and tonight Im going to add a 32oz tank in the system, as it currently sits it has 2 plastic tanks that hold 118oz and this is just to short of a flight time for me. So I will make the 2 stock tanks Y and feed the 32oz old smoke tank then run it to the uat for more capacity and may help with my little air in the uat issue as pulling from one tank has to be better than pulling from 2 tanks with a Y fitting

OMG.. Why do people put them selfs threw so much trouble! UAT's are the problem! Just dont use them and you will be much happier. I stopped using a UAT years ago and have never had a flame out since the last time the UAT leaked air.. Use a paper pleated clunk. Not sure where to get one? Pull it out of your UAT LOL

UAT's are not a problem if set-up correctly - and the correct set-up is very simple even a caveman could do it .......:cool:

Check out if the ca for some reason don't end up in your fuel pump nozzles or the fuel valve .pull all the clunk to the Sullivan xl and the fuel lines and vents to large tygon and all should be good.

I wonder how important UAT's are now that all turbines don't necessarily flame out due to a bubble? I know kingtechs will run pretty well with bubbles as long as they are not continuous. The Jetcat will flat out stop if it gets a bubble though. At least that has been my experience.

Not using a UAT will greatly reduce the risk of getting ANY bubbles....So why use em? There is a least 6 points that could develop leaks with a UAT.

But getting back to your post.. I did have a P-80se that ran for quite awhile with an airleak till I found it was the cap on the UAT getting loose and not letting it get full rpms

Well I got four more flights on it today and it just seems like one side of the two tanks always seems to have a little bit more fuel than the other one I take it apart I can't tell any difference between the two I'm not worried about it anymore got a guy who's building a third tank for me so I can add some capacity and I'll just have the two tanks Feed into that one large tank then to the U a T I think that'll take care of my issue

Reasons why you might want to use them too.................. clunks can spend alot of time in air!

https://www.youtube.com/watch?v=WtbSqEtLQX4

marcs

I've had the same experience, had an F-16 where there just wasn't enough space for a UAT......flew fine without it, and I flew it hard all the time.

Just like everyone seems to think that fuel tanks need to be made out of kevlar............no benefit. They break the same.

Andy......all marketing. If the right person tells you that you need it...........you will need it. '-)

you may wan tot check the length of the fuel lines going from the "Y" to each tank. They need to be the same length.

Great to know you find the problem without a killer flameout.

A CA clog remembers me a thing happened here a few years ago. A doctor in a heart, open chest cirurgy frustrated with a pacient wich he was about to loose, in dispair asked the nurses to go to the convenience store near the hospital to buy a CA bottle to try to glue together the heart tissue of the pacient. It worked and the pacient survived Nothing to do about jets, but well... is a interesting story. :D