Engine tuning advice please!

[expo]

I've got an old ASP .46 on a plane and it has suddenly become idle fussy. It will start and idle for about 30 seconds and sputter out. It seems to run well at full throttle. Suspecting the glow plug I changed it out to another with and idle bar and it ran the same. Have tweaked the idle adjustment screw through a whole range of settings. Any suggestions???

[tailskid]

Fresh fuel? Or stale?

Jerry

[expo]

Fresh fuel? Or stale?

Jerry

Yes, fresh--less than a month old 15% nitro which I've been using all along. I thought maybe a leak in the gas tubing so I put fresh ones on and tested the gas tank for leaks--OK.

The idle needle valve on the right side of the engine; is it in for lean and out for rich like the hi-speed? It will idle screwed in a little more but the transition to full throttle is with a little hesitation. It won't keep on idling either way.

[tailskid]

" is it in for lean and out for rich like the hi-speed? "

Should be...

Jerry

[waterloged]

Check for loose or leaking crank case covers and gaskets, If it runs good at high speed but dies on idle itcould be leaking air or vaccum in the crank case. the other thing to check is fuel line or clunker and make sure its not half pluged.
Waterloged :D

[expo]

Pulled the engine and found nothing wrong--pulled the gas tank and where the fuel lines went through the rubber seal they were rusted through and fell apart. Cleaned it up and installed new brass tubing. it must have been sucking air or losing muffler pressure at idle. Good advice waterloged, thanks.