Scenario: Brand new .63 (old style with intergal regulator), F plug, PM 20/20, 13x6 APC, tank with nylon strapping tape, filters on both lines, fuel system consistently holds pressure. Engine will start without incident and run "ok", tach'd about 11K with current prop and there's approximately a 1/2 gal. of fuel through the engine at this point. Problem: engine intermittently quits; it will quit both at idle and partial/full throttle. When it does quit, it's immediate- as if you'd turned off the ignition. Indications: at approximately 1/3-1/2 throttle, engine seems to run erratically as if rich; when the feed line to the carb is squeezed to limit fuel flow, it seems to smooth out. The regulator was- from the factory- slightly proud of the body; I've incrementally tried screwing it "in" to limit fuel flow through the transition but this seems to have little, if any, effect. Thinking there was possibly dirt or crud in the regulator, I disassembled it but it seemed to be free of any foreign objects. The plug has been changed- out of desperation- and that didn't have any effect. Also, I've tried running it with the glow ignitor on vs. off but can't seem to discern any difference. Checked the valve clearances and they also appear to be good.

Last season I ran another .63 (late model with reg. on pushrods) without incident and never touched the needles after their initial adjustment. I try to be careful about my setup of engines and fuel systems and feel fairly confident of the integrity of the fuel system. This situation has me completely baffled (and pretty discouraged); I'm ready to take a hammer to the whole works but have managed to restrain myself (there's always tomorrow!).

Any thoughts?

Does the engine leak fuel into the carb when shut off with pressure in the tank? A little drip won't bother but more than that indicates a regulator problem.

I had a similar problem when breaking in a YS 63 with a test mount. If you eliminate the usual fuel line and tank problems, check the prop hub/washer/prop to see if it is slipping. If the prop slips, the engine will stop immediately at wide open throttle. It has been my experience that ABRUPT stopping is caused by the glow plug coil vanishing or the prop slipping on the hub (or running out of fuel).

Forgot to mention the engine is inverted.. It seems to intermittently leak fuel from the carb but that seems to have tapered off a bit as I've run the engine a bit more. My other .63 is inverted too, and a bit of fuel seems to drip intermittently- but it runs fine. On the other hand, the plane (the one I'm having trouble with) will sit for an 1/2 hour plus and still have plenty of pressure in the tank when the fuel dot is removed to de-fuel.

Sam,
Pick up a gallon of Cool Power 30% heli fuel, then go to www.ysperformance.com and follow my running instructions.

Let me know what you find.

Thanks, Dave

Dave,

Per your comments I tried the 30% Cool Power fuel, still "no dice". I've tangled with a number of different engine problems but this has me completely stumped. Any other ideas or is it time to send it in? (hate to do this with a brand new engine). The big hammer I have is looking more and more appealing the more I play with this engine.

It's either the hammer or send it in.

Your choice, I'm sure Richard can fix it.

hi there samD

to be honest i think it would be a real shame to get rid of such a beautiful engine,
i recon you should send the engine back to ys at there service department and have it serviced they do this free of charge cos they stand behind there engine that much and to spend the best part of £250 on an engine and then to get rid of it is a real shame im running a 63 on my extreme lite and have been experiancing troubles with it but nothing a good service should fix just a theory but have you adjusted the tappet clearnce and are the valves in perfect sic with tdc?

update me

plane kissa, please read the rules for posting and don't hijack other people's thread.

Thank You!