What was found
DURING TEST FLIGHT AFTER INSTALLING FACTORY REBUILT ENG, FUEL PRESS DROPPED FROM REQUIRED 186 POUNDS PER/HR TO 80 POUNDS PER/HR. A SAFE PRECAUTIONARY LANDING WAS EXECUTED. UPON EXITING RUNWAY, ENG STOPPED RUNNING WITHOUT PULLING THE MIXTURE. EXITING ACFT, FUEL FOUND RUNNING FROM LOWER COWL. REMOVING COWL AND INSPECTING FUEL SYSTEM, DISCOVERED B-NUT ON HIGH PRESS FUEL LINE FROM FUEL PUMP TO FUEL CONTROL WHICH IS INSTALLED BY FACTORY, LOOSE. THIS NUT WAS MARKED WITH ANTI-TAMPER PAINT BY THE FACTORY AND WAS INSPECTED AND FOUND TIGHT. PREVIOUS TO FLT, FULL POWER RUN-UPS AND FUEL FLOW CHECKS PERFORMED IAW FACTORY GUIDE LINES FOR ENG. POST-RUN EXAM REVEALED NO LEAKS.