DLE55 Dying

Started about 2 months ago the Cap would fly fine and after a few minutes the engine note would change and losing power at top end. To keep it going I would come back to a half throttle. It would get me nearly back to the strip and then it would die. On the ground it appeared to run just fine. Anyway, stripped the carb and cleaned it out and refitted. Back to the field and re-tune and fly. Flew for about one circuit and started to flounder and then died. Am I going to make it back? Nope! Luckily as it went down the south field and disappeared below the bank height, I managed to keep wings level, I gently pulled up on the elevator. Kevin and I found it happily sitting on the field undamaged. :whistle:

Due to the weather I was unable to get the engine off again until today. Looking at the removed carb the filter had some greyish gunge covering it. It appeared to be minute grit like. Cannot be grit. I think it is fuel tubing breaking down as the only answer as the carb was only cleaned out two flights ago. Anyway I have stripped the carb out again and stuck it in Peter Willis's ultrasonic cleaner (thanks Peter) and then fitted a new kit. I think I will add another line filter between the tank and carb and re-plumb lines. If this don't solve the problem then it has to be electrical failures. I don't fancy anymore Power Scale Gliding.

Are you talking about the gauze filter from the carb pump chamber to the regulator needle. If so, I found this filter blocked with a sticky gunge when i used Deluxe materials 2 stroke oil. So what oil are you using ?

Provide you use a felt chunk filter, no further filtering should be required and extra filters are a possible source of air entry.

Oil is Halfords for motor bikes. Could not get hold of Fuchs racing oil. Felt clunks? In short supply unless you want a giant size one.

Stripped out the carb again.  Gave it a few minutes in the ultra-sonic cleaner using white wine vinegar.  Re-kitted it and replaced the fuel lines. Waiting on better weather to start it up and retune

Sunday, 29th January.  Took the CAP232  up to the field. Got it started once fuel was pulled up. Will not rev over half throttle - dies. Fiddled with it for a bit but still no joy.  Now I am thinking!  Have I assembled the carb correctly?  Jets were set at factory default.  Is there some gunk still hiding in the main port?  I may have another carb somwhere so I will re-kit that and see what happens.  So frustrating. 

Deja Vu, didn't it turn out to be the ignition unit last time this happened to you?

No, I have not changed the unit. (It was the Extra GP38 that we changed the unit)   Engine was running fine until sometime last November when Jon went to use it. Died after a few circuits, felt like fuel starvation. Naturally stripped carb and tried again. Did it again but appeared okay on the ground. Stripped it out again and had to wait 2 weeks for re-kits (royal mail strikes). Christmas week rebuilt it again. Been waiting for fair weather and well here we are, anything above half throttle cuts out.  I had thought about changing the ignition unit, maybe it is not advancing enough or just giving up as rpm rises. I will see if I have spare until somewhere and try it.

Well its either lack of sparks or lack of fuel - The latter could be one of a dozen faults but the former is one these 
Plug
ignition unit 
crank sensor / wiring
Ignition switch 
battery 
I agree you need to eliminate these

HAVE YOU ACCESS TO THE RCEXEL TESTER - i have one 

Hi Kevin,
No I do not have a tester. If it stays dry today, I will temporarily plug in a spare ign unit (ex Dave Bright) and see what happens. I have also found a spare carb (also ex Dave) that I will re-kit as a stand by.  If they don't work I can always blame Dave, albiet he gave them to me when I bought his DLE55 back in 2013. 

Have you been using E10 petrol? If so, perhaps it has affected the characteristics of the carburettor's diaphragm in some way. You seem to get the problem in the air, starting is OK though. Could it be that the tank vent  has become partly obstructed? I remember reading about a two stroke petrol that kept failing. The reason turned out to be faulty roller bearings in the con rod. They were crumbling and the fine metallic particles were causing the spark plug to short out. I had a problem with my two stroke powered leaf blower, starting was good, but failed to run. The cause in that case was a delaminated fuel tube, a sort of woven Kevlar thing with an inner and an outer, the detached inner collapsed shortly after the engine was started, took me ages to find the fault.