Briggs & Stratton Excess Fuel/Oil and Choking Out

 

Ok, if not much help, try disconnecting the crankcase vent hose from the intake track & 
see what happens..
 
 
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When you say "only a very small improvement" are you looking at it from the amount of oil and smoke out of the exhaust? If the muffler had oil spit into it, it will take a while for it to burn off, so looking at the exhaust for too short a time will make it look like there's little improvement.
 
I would, in addition to what's already been said, suggest you take a look at the engine oil. Is it very thin and seems to be too much? That might have happened if the float valve didn't cut off the fuel flow and the fuel kept flowing (because of gravity) even with the engine off. The fuel might dribble into the cylinder, through the rings, and end up in the crankcase, diluting the oil. If that indeed happened, you'll need to change the oil right away.

Alright, I tried unplugging the breather tube from the carb, and now as I expected when running (which it does now, though still with a bit of smoke), there is fuel with some oil literally gushing out the tube.

I'm less familiar with everything that could cause this but it seems to me that would be a gasket blown somewhere. Although, where and what gasket could be holding back that much fuel? I know something major blew to cause this, but I'm still a bit mystified as to what the cause would be without tearing it apart.

I don't think I mind tearing it apart but I'd like to have some idea going into it where to look for problems.

Anyway, thanks for you help guys!

Oh, I did check the oil a bit and while it did perhaps seem slightly thin, it was nothing at all like what was coming out of the breather tube. The oil was a good pretty clean color and decent consistency. The tiny bit of thinness might easily be attributed to the heat wave we're having. The mixture coming out the breather was mostly gasoline (smell and consistency) but was quite dirty looking.

If you have a blown head gasket, you can diagnose with a leak down test.
 
Also:
https://www.youtube.com/watch?v=65GjCDnw_f4
 
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Perhaps indeed you've blown a head gasket, but I don't see how that would exhibit the symptoms you describe.
 
If we're really talking about the breather tube, one end goes to the carburetor (or intake manifold) and the other to the crankcase. If you've disconnected the carburetor end and stuff is coming out, it must be coming from the crankcase. The only stuff in the crankcase is oil and piston blow-by. The blow-by creates pressure which is relieved  through a one-way valve to the breather tube. I can't imagine that the blow-by is so dense in fuel that it actually looks like dirty fuel. That would mean that a huge amount of fuel in the piston is not being burned and seeping past the rings. First, I'd have to ask how so much fuel would get into the piston. OK, maybe the carburetor is dumping fuel in, not atomizing it. But then, second, I'd have to ask how is it possible that the rings are so bad that fuel pours past them, yet the engine is able to run.
 
Tests I suggest:
 
If you remove the carburetor entirely and shoot starter fluid into the intake, the engine starts, right? If you continue to quirt a little fluid in past the initial start-up shot, can you keep the engine running? And while you're doing that, is a sizeable amount of stuff still coming out the breather tube? Does it seem like more coming out than you're shooting in?
 
If you remove the carburetor, disconnect the spark plug, and crank the engine, does stuff still come out of the breather tube?
 

Yes, please keep us updated. I find it intriguing.