cymaz Posted May 21, 2019 Share Posted May 21, 2019 With the arm and needle there is quite a bit of “play” before the needle comes off it’s seat. The needle seat tool is an absolute Godsend. I have a carb rebuild set and gasket set coming soon for my recalcitrant engine. On careful hearing I can make out a sucking sound when turning the engine over by hand. I’m still not sure if-its a leak or the pulse port Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 21, 2019 Author Share Posted May 21, 2019 Posted by cymaz on 21/05/2019 21:06:16: With the arm and needle there is quite a bit of “play” before the needle comes off it’s seat. The needle seat tool is an absolute Godsend. If you use it correctly! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 24, 2019 Author Share Posted May 24, 2019 Posted by Martin Harris on 21/05/2019 19:18:05: Posted by cymaz on 23/04/2019 17:03:46: RESULT ! Yes, no and eventually (I hope) yes... ...but I'm as confident as possible that there's every chance that with the gasket problem having caused the pumping problem and the needle valve now operating correctly, there's no reason not to expect success. Famous last words! I took the model to the field yesterday and told a few people that I could get to listen that I'd found the reason for its reluctance last time out, expressing my confidence before taking it on the long trundle to our "bottom" pits. I applied choke and starter...nothing. Hmm, perhaps it didn't need choke...still nothing. Disable ignition and spin it over with the throttle wide open to clear any flooding...nothing. Here's where things got slightly odd, plug out and it looked a bit wet so borrowed a blowlamp to dry it out. Nothing. Check for spark...difficult in the bright sun but is there one? Borrowed a new plug from a clubmate. No, still not even a cough. OK, all I've done is add the cowling since it was running perfectly so although I couldn't think of anything that would affect a magneto engine, no electrical connections except the plug lead, but off with it to have a look "just in case". Nothing adrift. By this time, the continuous returns to the other end of the field (each stage of the investigation needing one) were getting rather frustrating so I took the model back to the clubhouse pits. I took out the crankcase drain plug and injected a few drops of fuel...success...then the prime ran out and it stopped. Again to check with the same result. Fuel checks ended up with a piece of fuel filled tubing attached to the inlet which resolutely refused to move as I cranked so it must be fuel pump again. Put some tubing on the pump diaphragm cover vent and gently blew and sucked - the level dropped. turned the engine over and the level dropped some more. Connected the plug again and cranked the engine - "Woo Hoo" it ran until the fuel in the pipe ran out. Connected the proper fuel pipe and away it went. Static run was fine so (luckily the wind had started to swing round and everyone had returned to the top of the field) taxied out for a very successful flight. I have to wonder if this is a new problem or an intermittent one which has affected my investigations at various times...although I did change the pump diaphragm at an early stage - perhaps I'd better run a pipe from the vent system to apply mouth to mouth resuscitation in case (or perhaps I should say when) it happens again! Quote Link to comment Share on other sites More sharing options...
cymaz Posted June 21, 2021 Share Posted June 21, 2021 Just to update this thread... Had an issue with my G38. It wouldn’t run for long, about 5 secs at most. Reset the needles, no change. Checked the fuel, batteries. All the usual stuff. It turned out to be a bad plug. Luckily I had a new BPMR6A. All was well. It never occurred to me that a NGK could fail like that! Quote Link to comment Share on other sites More sharing options...
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