When I got the engine back from YS I installed it in my plane & tried to pressurize the tank without any fuel, leaving the regulator adjusted just as it came from YS. I think this would eliminate the question of bad/dirty fuel. As per my earlier post I adjusted the regulator about 3 turns in from flush & was holding pressure. Let it sit all night then realesed the pressure, pressurized the tank again & off to work I went. After work it was still pressurized so this would eliminate a leak in any of the fuel lines. As the regulator is adjusted now if I turn it in another 3/4 turn it bottoms out. Will try running it this weekend & further adjust the regulator.