I went up today for a few laps at 3000 over Paine Field. The engine ran well below the staging point, but started stumbling when above the staging point. It ran smoothly through the staging transition on the ground, but when in the air I could not tell by the mixture monitor if it was lean or rich. I tried leaning it out and richening it up, but results were inconclusive so I stayed below the staging point for the remainder of the flight. I'll tune it in flight when I can get higher.  Temps were down around 130 degrees at 4800 RPM and 110 mph, MP was not noted.

I accidentally hit the cold start switch while on downwind with two other planes ahead of me, and  the tower told me to go around on final with the engine stumbling badly, but the plane ahead turned off onto the taxiway just in time so I told the tower that I would really like to land, so they cleared me.I still had 7000 feet of runway ahead of me.  The engine died as I turned off onto the taxiway and then I noticed the cold start switch. The first order of business was making and installing a switch guard for the cold start switch. I'm also going to pre-load the switch with a rubber band so it stays in the off position unless I'm pushing it on, and can just pull the rubber band off of it if I need to shut down a set of injectors and run the remaining injectors on cold start.(limp home mode for failed injector.)

The fuel self transferring issue was resolved by installing manual valve on the transfer line between the tanks.



Brian Trubee

Dave Leonard had an off airport landing because of that cold start switch.
One can get a flip up guard that covers the switch to prevent inadvertent
operation.

"The fuel self transferring issue was resolved by installing manual valve on the transfer line between the tanks."

Are you sure about that Brian?
Did you notice the fuel pressure when the engine starting running rough?
Could be you sealed the right tank when you closed the transfer valve.
I suspect the right tank vent is not working.

Paul Lamar