What was found
AIRCRAFT WAS GROUNDED: AIRCRAFT HAD SUBTLE HINTS OF ODOR SIMILAR TO SOF EVENT BUT NOT BAD ENOUGH OR PERSISTENT ENOUGH TO WARRANT ACTION AIRBORNE. IT WAS NOTICEABLE FOR A SHORT TIME DURING ENGINE START AND TAXI BUT THEN DISSIPATED, AND AGAIN IN A SIMILAR FASHION BUT NOT LONG ENOUGH OR PERSISTENT ENOUGH TO WARRANT ACTION AIRBORNE. I DO THINK THE POTENTIAL EXISTS FOR IT TO GET WORSE AND THEREFORE AM REFUSING THE AIRCRAFT. MAINTENANCE FOUND FUEL CONTROL UNIT LEAKING AND REPLACED IAW AMM 49-32-11.