My engine started giving me trouble today. I'm still basically bench testing and finishing up some build stuff. The only two things I've changed are that I installed a fuel filter and was running with the cowl on. Engine runs for a minute or so than stalls. The fuel line seems to have a lot of bubbles in it. How long should I be able to run with it on the ground before taking off? I realize it won't get the cooling it needs just sitting on the ground but it seems like it should run longer than it is.