Followup to my engine problem (possible resolution)
I'm happy to report that I believe I may have finally found the source of the intermittent mis or stutter that my Superior IO-360 has had from day one in my Glasair. A week or so ago, I decided to (once again) test the fuel supply to the engine. I attached a clear hose to the output port of the gascolator. I turned on the boost pump and after getting a solid column of fuel exiting the gascolator, I began to notice air bubbles on a regular basis come down the clear line. In order to isolate the component causing the problem in order to rule out a fuel plumbing air leak or a faulty fuel valve, I connected clear tubing to the input and output ports of the fuel pump (Weldon brand) and ran them into their respective fuel cans. Turning on the pump, it quickly became clear that the Weldon pump was introducing air into the fuel system. I discussed the matter with Don Rivera at Airflow Performance and he agreed that it appeared the Weldon pump probably had a leaky shaft seal (I sent him a video of the air bubbles being pumped thru the clear line by the Weldon pump). Unfortunately, the Weldon pump cost about $700 bucks to overhaul, so I ordered up one of Don's new style pumps for quite a bit less. I got it installed this weekend and even verified that it was not producing any air like the previous Weldon Pump was. I flew the plane for about 45 minutes late this afternoon and I do believe (fingers crossed), that my problem has truly been resolved. The engine ran VERY smooth. Not one hiccup, burble or stutter like I've nearly become used to over the past 300 hrs. of operation.
So, IF my problem is truly resolved (time will tell), the lesson I need to take away from this experience is that air in the fuel system can most certainly produce an engine symptom that feels and sounds exactly like an ignition problem, a sticky valve, or possibly something similar to detonation.
By the way, about a year ago, I ran clear tubing between the fuel servo and the flow divider and then ran the engine. There were no visible bubbles in the line, so I declared that fuel supply was not my issue and went on to chase other potential ignition related possibilities. I have no idea why there were no bubbles in the line that day. Maybe the Weldon pump was having a good day,,, who knows.
I'll put some time on the engine and will report back whether my engine symptom STAYS fixed. I do appreciate everyone on the VAF that has helped me troubleshoot this issue.
Best,
Chad