I think that I've found the problem that I had at WOS earlier this month. The engine was down on power and at about 5,000 in 2nd it started mis-firing and then quit completely. I coasted as far as I could off the course but it didn't get quite as far as the return road. A USFRA official towed me over to the return road, he worried about running over the timing wires but we did it without any problem.
When we got home I was able to crank the engine over on the starter but purposely didn't fire it up. Yesterday I removed the hose from the carb manifold and used the electric fuel pump to pump two gallons of fuel from the fuel cell into a fuel can. It took about a minute but I noticed that the flow was not a clear liquid. There appeared to be some froth in the fuel as it went into the can. The sound of the pump running sounded a bit funny, too.
I have two filters in my fuel lines, one 100u filter between the fuel cell pickup and the fuel pump inlet and another 10u filter on the pump outlet. I found out that my "100u" filter element is actually 10u !!! No wonder I was getting fuel starvation. Sucking fuel through a 10u filter together with a pressure altitude of 4200 ft was causing my Carter electric fuel pump to cavitate. I'll replace the inlet filter with a Kinsler 140u filter that I have on the shelf.
Before the run my main power relay failed; the contacts were open even when its solenoid clicked in. I jumpered around it with a short wire and clip leads so I did have 12V electrical power but the voltage drop of the jumper may have made the fuel pump voltage a little low. I'll take the relay out and disassemble it to have a look at the contacts.
Regards, Neil Tucson, AZ