Thanks, Chuck. That's exactly what I was looking for. 16" of water is about 0.578 psi. Glow fuel, mostly methanol, is less dense than water so I estimate the 16" of glow fuel is about 0.48 psi. I can blow a lot harder than that!
The fuel system was tight. The problem was OSF (Operator Skill Factor). I'd left the throttle open while refueling and some fuel ran out the carb and into the cowl. Verified that as the problem this morning. Fortunately, I did not have to fix the fuel tank as I'd done that a couple of months ago and it is a hassle to get the tank out and in, not to mention bending the lines into the tank.