Update on my situation with this same problem.
So, I replaced the intake gaskets, still nothing. I took off the air filter cover and covered the intake with my hand, still no cold start. I also blew out the fuel lines, and replaced the fuel filter (again) just in case. If I prime it, starts right up and stays running. It will only start back up without being primed if I run it for 15-minutes or more.
Previously, I replaced the following:
- plugs (correct gap, verified spark)
- fuel pump (verified it is working correctly)
- carb (new gaskets came with it)and solenoid (verified solenoid is getting 13 volts)
- air filters
- fuel filter