Glow Idles Then Stops

This seems to come around about every six months to my four strokes (Wots Wot) and two stroke. Both start easily, throttle up perfectly. Taxi out to strip, look left and right, call taking off and find the engine has stopped. Back to Pits, fiddle with main jet, change glow plug numerous times back n forth from strip. Can't fathom this out! So, today in advance of some fuel lines and bungs turning up tomorrow, I have stripped the fuel system on the Curare initially. Really hoping I have covered all possibilities. Or something else?

If it's failing during the taxying process it's more likely going to be the low end needle, not the main jet! I flew glow for 10 years before electric and would very rarely need to change any settings on a motor. The low end needle was always worth playing with to get a reliable tickover and fast pickup. There was always a little compromise between getting the smoothest/slowest tickover and the fastest/cleanest pickup. The only other thing to consider is that when I only flew glow, I would go through a lot of fuel and it was always fresh. Now that you are mixing and glow and electric, are you using enough fuel to ensure that it is 'good'?

Mike is correct (of course ) cutting on idle would be low end needle not high end.

If it just fades and stops, it is likely to be lean, if it gets lumpy and dies it's probably rich.

Accelerating from idle, if it takes a while to clear, it's rich, if it tries to stop immediately it's lean.

But as Mike says, unless your fuel or plug has gone off or you have got a blockage, then it shouldn't change

It was suggested at the field on Monday that after a long period the tank bung perishes although hardly noticeable to the naked eye but releases tiny particles which would be enough to play up the idle at least. Fuel is Model Technics Contest 10 and less than 6 months old.

If the bung perishes it usually leaks.

Do you not use a quality filter in the fuel line from tank to carb?

JonTappin wrote: If the bung perishes it usually leaks.

Do you not use a quality filter in the fuel line from tank to carb?

Yes it has a carb filter - depends on what you call quality. Filter in refill bottle, filter in line too That makes three. A small red one that can be unscrewed for cleaning. That appeared spotless when I took it apart today.

I had the same problem with an OS 70 fourstroke in an AcroWot. The problem turned out to be that the tubes through the tank bung had corroded. This was spotted by an eagle eyed helper who asked why the fuel line to the carb was full of bubbles. Flushing the tank and fitting new tubes made sure that the engine ran reliably again.