Originally Posted by
earlwb
Did you make sure that the passage that lets the crankcase pulses get to the carb pump are open and clear?
There is a passage to allow for the crankcase pulses to reach the pump diaphragm so it will move back and forth and pump. If that passage is blocked (eg putting the carb on the other way) then it won't pump. Some engines used a fitting and a short length of tubing to route the pulses to the engine too.
Some carb gaskets only have one pulse hole. If that's the case and its upside down it won't pump. Right-o. But without changing anything, and it won't run for guy A but it will run for guy B tells me it's got something to do with where the engine is being run (or attempted). A test stand with a known good fuel system is paramount to weeding out engine problems.