Engine quits

I am experiencing what I think is a fuel-related shutdown. The engine starts and runs fine for about 30 minutes, then quits. I can't get it to start again for about 10 minutes, then starts and runs fine for another 5 minutes before shutting down again and so on. The ignition spark looks good and the temp gauge never gets above 180. Do you have any good suggestions for how can I verify that the engine is actually quitting from lack of fuel?

I have rebuilt the carb, replaced all the fuel line and inline filter from tank to mechanical fuel pump, removed fuel tank and inspected the pickup with no change in symptoms. The only thing left is to rebuild the fuel pump, which is planned for next week.

[Don Moyer]

Remove the flame arrestor and check for the presence of raw fuel. If the choke is closed completely, there should be raw fuel puddled in the bottom of the intake throat within 15 to 20 seconds of cranking (3 or 4 five-second attempts). If the carburetor intake throat is "bone dry" after this amount of cranking, the reason for the non-starting is either a problem in the fuel supply which prevents fuel from getting to the carburetor or some problem within the carburetor that prevents the fuel from getting through the carburetor (most likely a blocked main jet).

Don