Evening all:
I've been discussing these problems with Mike Farley recently...let me give a quick synopsis:
Last flight I took in mid-February was pretty uneventful, however I noticed that the engine was developing a "roughness" at cruise speed and the throttle was balking a bit after landing. I had about 46 hours on the engine at this point, and had done a valve adjustment just before 40 hours. Feeling like maybe I had the mixture set a bit too rich during the winter, and possibly fouled the plugs, I decided it was a good time to check these, change the oil, and prepare the airframe and engine for spring. Here are the items I did (in succession):
1. Changed oil (did not remove or clean oil screen).
2. Removed all 8 spark plugs, and judging condition ordered new ones (same brand and type as recommended - Autolite 4163).
3. Gapped and installed 8 new spark plugs.
4. Cleaned and oiled K&N air filter
5. Adjusted mixture 1/2 turn lean (had adjusted it 1/2 rich in late November).
When I went to restart the engine...it didn't want to start. Once I overcame that problem (had to open the throttle more)...it didn't want to keep running. After many cycles of starting, briefly running, stumbling and dying, I was able to coax the engine to run...somewhat.
I checked the obvious items like spark plug wires mixed up. That wasn't the problem. I was getting fuel. So maybe the "clean/oiled filter" was choking the intake? Removed the filter and ran it another day, to take these videos.
1st video is of a full static power run, you can see it reacted okay to this test, until I powered back below 1500 RPM and the engine quits
https://youtu.be/WRqejJy7esM2nd video is a mag/coil check, it's showing a much larger RPM drop then usual. I've not touched the secondary ignition trigger timing:
https://youtu.be/ExlxHtATG6EThinking maybe some of the new spark plugs were bad, I cleaned the original ones, and reinstalled them (that didn't help). Mike was thinking maybe the mixture was too lean, so I reset the mixture back to my "winter" setting even though OAT's are back in the 50's to 70's. That didn't help so I richened it up again today another 1/4 - 3/8 turn. No joy.
Another item to note. In December I began to notice a increased fuel leak at the finger strainer and shut off valve. The teflon paste is breaking down from exposure to 100LL. I have not refueled since early February and had about 6-7 Gallons of 100LL remaining on board after sitting for 4-5 weeks. I have never used anything but 100LL with this engine.
Beginning to wonder if I have contaminated fuel? Or water in the tank (although sample was clean and clear blue). Or crud has passed through the strainer, gascolator and clogged,the fuel passage inside the AeroInjector?
At a loss. Engine is completely stock setup. Has run very reliably since I got it dialed in last year, and completed Phase 1 testing with no hiccups at all, until now.
Also checked the other key items (intake hoses are tight and no air leaks), all ignition wires are in good condition and properly connected, throttle plate is opening and closing correctly and mixture control is still set up per manual.
My next step is to drain the tank, take apart the fuel line fittings, shut off valve, and clean everything including the AeroInjector and reseal the fittings with EZ Fuel Lube (got this from Aircraft Spruce recently).
What am I missing?