I got a friend that's working on a Mariner. He says it starts, runs fine at an idle but when it's put under a load, it runs for about 10 minutes and completely dies. It will re-start most of the time, but runs like crap til it cools down. Not that these things are the problem, but he has changed the key switch, fuel pump, squeeze bulb(and it's installed in the right direction), and he's checked for spark and it's good. I tend to think it's not carbs, they certainly wouldn't all stop working together at the same time. Would they? I told him the power pack could be going bad, but he says when it happens, it still has spark. Seems like it wouldn't when it acts up, only when it has had time to cool off. Maybe foreign crap in the fuel tank? Collapsing lines? Any ideas?