Joe I would check your fuel tank vent tube to be sure it is not pluged with an insect or something? Mike Turner Jackson Mo ----- Original Message ----- From: "Joe H Horton" <joe.kr2s.buil...@juno.com> To: <kr...@mylist.net> Sent: Sunday, July 30, 2006 7:55 PM Subject: KR> still searching
> > Guys, > For the past week I have made some kind of adjustment, change > or > check in the engine compartment trying to find any source of a problem > from my engine out 3 weeks ago. I have a small stumble that I can now > get to happen when running on the ground. I did not have any hint of > this problem before I started my annual inspection. So I have been > concentrating on the things that I touched during the inspection. > To recap a little the ignition has been completely checked out > as > well as the engine itself. This left fuel delivery and carb. The fuel > lines where > checked and flow was verified to be more than ample. > I have about 4 hours of ground run and fast taxi test over the > past week. I thought that I might have it licked yesterday so I > tried a flight test. I tried to duplicate the flight take off from when > the engine stopped. The temp and density altitude were almost the > same. The run up and take off and the climb all went without the > slightest > hick up. I climbed to 8500 ft while circling the airport. (@ 800'/min) I > > circled for awhile and reduced throttle to 2750 rpm. About 20 min had > gone > by and not so much as a hint of a problem. I leveled out to the west an > noticed that my indicated airspeed and ground speed were almost > identical. > This made me curious and distract to check true airspeed on the gps > E6B calculator. I found that I was operating at a density altitude of > 10500 and true airspeed was 139 mph at 2750 rpm. by now I was 10 to 12 > miles to the west and I decided to go back to full throttle. I was leaned > > out during this time also. > When I went to full throttle it started to sputter and spit and > just plain act up. I went full rich (while turning back) That did not > clear it. I reduced throttle and that did not return it to smooth. > These > were not sudden or panicked throttle changes. I moved the throttle > slowly > and methodically to try and figure it out and analyze what was going on > with the instruments. The only instrument that gave me any clue was the > mixture gauge which went to full lean with every sputter. I also tried > switching back an forth the 2 ignition systems. That made no difference > either. The last resort was to try carb heat. That did have an effect on > it and the engine recovered in a matter of 5 to 10 seconds. The mixture > gauge showed that it enriched the fuel to a normal level. I did not try > full throttle the rest of the flight and I did try going back and forth > with the carb heat. After the roughness stopped the carb heat just > dropped the rpm but showed no other effect. > As a side note the air temp at altitude was 59 deg. and I was > at > least 1000' above the haze layer(no visible moisture) > This morning I took the fuel system apart again and flushed it > out and check flow. I ground ran it for about 30 min again. I can get it > to do the stumble on the ground now but the engine has to be completely > up to normal operating temps. I.E. the oil has to be around 220 deg. and > oil pressure is 35 to 38 psi. cylinder heads are all around 350 deg. > The > exhaust temps are the only other clue that I am finding something that > I > never had before. All my time before annual inspection at cruise I > would > set the mixture for the highest exhaust temp to be 1330 deg and they > would all fall into a 20 to 30 deg range. Now at 1330 and all temps in > the normal range the exhaust span while not get closer than 120 deg and > I > have to set it for more like 1300 even to stay out of the stumble > problem. > The way that I can get it to start the stumble problem on the > ground is to lean it out. If I leave it full rich it does it only > occasionally and with not set pattern or time between. It is also very > brief like that too. > Any thoughts or other information needed. > Joe Horton, Coopersburg, Pa. > joe.kr2s.buil...@juno.com > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
