shmkr,

The contents of the fuel bowl in the carburetor won't allow the engine to run for 1/2 a hour if there were a fuel supply problem. To cause the problem you describe, the fuel flow would have to be experiencing a intermittent blockage. Any broken or partially plugged line would be static...it wouldn't allow the rig to run for 1/2 an hour then shut it down, it would happen consistently and much sooner than that.

Have you made sure the floats are nicely centered in float chamber and that they aren't hanging up and shutting off the flow. You have replaced all the components from carburetor to tank including the fuel pump and still have the exact same problem.

I am guessing your tank has a bottom tap and maybe a small neoprene flex line from tank to hard line. That flex line can become soft and sometimes collapse, cutting off the fuel flow.

A mechanical fuel pump has the ability to pump air as well as fuel. The air exits the bowl vent in the carburetor. Even with some air present, there should be fuel too. I think the key here is how long the rig runs before it fails.

Stuart