Honda Harmony won't start

I have a Kohler courage 23 (cub cadet) motor that will start, but blows thick white smoke and gas out the exhaust pipe? I removed the feul pump and poured gas directly into the carb intake, it ran and no more white smoke came from exhaust, so I don't think any seals or rings, etc.. are bad. The compression is good, i can put my hand over the intake and it sucks my hand in very well. This pump is controled by the engine compression via a diaphram below pump creating suction. Not water cooled. It does pump the gas hence the ehaust spew and white smoke. Could the pump be bad, ie: possibly spilling the gass into the diaphram area (cylinder head)? Has anyone had to deal with this too? Thanks in advance to anyone who can help me.

Engine runs great a couple of minutes, but chokes down as oil shoots into carb. I changed the diaphragm (Valve cover) that connects to carb with a rubber tube. It ran great for a couple of minutes and then the oil blew back into carb. What could cause this?