JUST AFTER TAKEOFF, AND AT ABOUT 150 FEET AGL, THE ENGINE QUIT. THE AIRPLANE LANDED AND NOSED OVER IN A MARSHY AREA ABOUT 1/4 MILE FROM THE RUNWAY. AFTER THE FUEL SYSTEM WAS FLUSHED, THE ENGINE STARTED AND RAN NORMALLY. PROPER MAINTENANCE HAD NOT BEEN PERFORMED ON THE AIRPLANE ENGINE FOR THE PREVIOUS 18 YEARS. THE PILOT WAS ALSO OPERATING WITH A REVOKED PILOT CERTIFICATE.