As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE ACCELERATOR PUMP IN THE CARBURETOR FAILED. INSPECTION SHOWED THAT THE PUMP HEAD GLAND HAD SHRUNK, SO THAT IT DID NOT PROVIDE A SEAL BETWEEN THE CARBURETOR BODY AND THE PUMP ITSELF. THE RESULT WAS THAT ADVANCING THE THROTTLE DID NOT CAUSE FUEL TO BE SQUIRTED FROM THE PUMP EXIT ORIFICE. REPLACEMENT OF THE PUMP RESOLVED THE PROBLEM.