BIGBARPER

Hi Guys

I have a little problem............

At high power settings (P180) the UAT starts to look like its 'boiling' now I live in england so its not the temperature!! ie filling with bubbles and air starts to accumulate at the top of the UAT.

Done all the obvious things, wire locked all lines, tightened all connections, no air is coming from the tanks ( can see the line..no bubbles), tried a couple of methods of closing the fill line both I believe secure.

Tried a refill of fuel to get rid of all air in UAT, then ran it tipped so as to cover the two brass bulkhead nipples and saw one bubble appear at a nipple, so tightened (or rather tried didn't seem to do much) and that temporarily stopped the bubbles appearing.......but they are back.

So question is anyone ever had a similar problem? and how are those bulkhead nipples secured?

Thanks a million.

Phil.

3DHELINUT

My Feedback: (3)

Phil SWB uses red locktite on the barbed nipples when they assemble the UAT's, you will need to apply heat to loosen up the nuts. But watch out as you may melt the plastic in the process.
You can try some pvc cement to get a better seal.

Another suggestion would be to use a JMP fuel Accumulator, the UAT is not holding up to the negative pressure you are subjecting it to.




Alan

757Driver

My Feedback: (90)

Hi, I had a similar issue with the UAT fuel level dropping when I began to pull fuel out of the system during my fuel system test. I found a loose line that was allowing air to come into the UAT and that was allowing the level to drop. Obviously the path of least resistance will be taken. If it can draw air, it will! The UAT and all its connections must be air tight as it is operating under negative pressure to draw the fuel from all the other tanks.

Good luck mate,

Ron S

My Feedback: (2)

If you can't figure out further why the UAT is appearing to draw air, you may want to look downstream toward the tanks, and possibly enlarge the fuel lines you are using, or look for a restriction. This way, you are relieving the amount of pressure reqd to draw fuel quickly to the UAT at the high throttle settings. This won't fix your problem if the UAT is truly leaking - but it should increase the throttle setting where the bubbles will appear in the UAT.

pbusa1400

I had the same problem. I had several flame outs with my p-180. I switch to the Jet Model Products uat and everything works perfect now.

ckeene9

My Feedback: (-1)

On these larger engines we've had an issue also. Here's the BVM fix for this: http://www.bvmjets.com/Pages/Addendu...0Addendums.htm


Christopher

David Gladwin

I had a similar problem with the fuel system feeding the Wren XL 200 in my Hawk. The problem was fixed by changing the Orbit clunk as supplied by Jetcat to a Tillotson felt clunk.

The tiny mesh of the Orbit is fine for smaller engines but causes cavitation at high fuel flows, the tiny bubbles caused then accumulate in the header tank or UAT. Assuming your fuel system is completely air tight, this may very well be the problem.

Regards,

David Gladwin.

BIGBARPER

Gents

Thank you very much for all the information and suggestions, will post the eventuall fix

Phil.