I'm having a bit of an engine problem and I'm hoping someone here might have some ideas.
The engine was running great for 6 hours of my flight until only a few miles from my home airport. When I throttled back to slow and enter the pattern the engine started running very rough with visible vibrations of the cowl. Adding power helped it to run better but it still tended to sputter. I didn't spend much time troubleshooting in flight since I was so close to home. I just got it on the runway. When I pulled the power out over the runway the engine completely quit.
I was pretty tired from the trip so I let it sit over night and went back out the next day to troubleshoot a bit. I had thought that it might have been a carb ice problem or water in the fuel. I took fuel samples from both tanks and did not find any water. I went out and ran it up for about 10 minutes to make sure there was ample time for any water in the system to move through it and it still ran rough. I ran the engine as lean as I could get it in hopes of cleaning any fouled plugs. The egine would pick up a couple of hundred RPM with a fully leaned mixture and ran better but still a little rough. The airfield is at 1400 ft. Once that I decided that my attempts to clean the system of water and to clean the plugs was not really doing much, I attempted to shut the engine off. Throttle all the way back, mixture all the way back, the engine would continue to run but only barely. The only way I could get it to shut off was to switch the mags off. I tried it again running the engine to about 600 rpm and pulling the mixture and still had the same problem.
I read somewhere on this forum about a mixture idle adjustment screw on the carb that had vibrated out on some others and hoped that I had a similar problem as that seems like an easy fix. No such luck. The screw is firmly in place. When adjusting the mixture lever the mixture arm at the carb does go all the way to the stops.
I haven't pulled the plugs yet to see but I expect they are fouled out. Perhaps I was running the engine a bit too rich for the flight but I'm not sure. The number 3 cylinder was at about 1350 on the egt where as 1 and 2 were about 1160. That seems like quite a spread to me but I'm not sure if any of this contributes to my problem. The only other thing I noticed was my left mag was running a little rough during my runups during the flight. Switching from one mag to the other during my post flight runup did not make any difference on the engine roughness though.
Any ideas?
The engine was running great for 6 hours of my flight until only a few miles from my home airport. When I throttled back to slow and enter the pattern the engine started running very rough with visible vibrations of the cowl. Adding power helped it to run better but it still tended to sputter. I didn't spend much time troubleshooting in flight since I was so close to home. I just got it on the runway. When I pulled the power out over the runway the engine completely quit.
I was pretty tired from the trip so I let it sit over night and went back out the next day to troubleshoot a bit. I had thought that it might have been a carb ice problem or water in the fuel. I took fuel samples from both tanks and did not find any water. I went out and ran it up for about 10 minutes to make sure there was ample time for any water in the system to move through it and it still ran rough. I ran the engine as lean as I could get it in hopes of cleaning any fouled plugs. The egine would pick up a couple of hundred RPM with a fully leaned mixture and ran better but still a little rough. The airfield is at 1400 ft. Once that I decided that my attempts to clean the system of water and to clean the plugs was not really doing much, I attempted to shut the engine off. Throttle all the way back, mixture all the way back, the engine would continue to run but only barely. The only way I could get it to shut off was to switch the mags off. I tried it again running the engine to about 600 rpm and pulling the mixture and still had the same problem.
I read somewhere on this forum about a mixture idle adjustment screw on the carb that had vibrated out on some others and hoped that I had a similar problem as that seems like an easy fix. No such luck. The screw is firmly in place. When adjusting the mixture lever the mixture arm at the carb does go all the way to the stops.
I haven't pulled the plugs yet to see but I expect they are fouled out. Perhaps I was running the engine a bit too rich for the flight but I'm not sure. The number 3 cylinder was at about 1350 on the egt where as 1 and 2 were about 1160. That seems like quite a spread to me but I'm not sure if any of this contributes to my problem. The only other thing I noticed was my left mag was running a little rough during my runups during the flight. Switching from one mag to the other during my post flight runup did not make any difference on the engine roughness though.
Any ideas?