As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH APU RUNNING & APU BLEED AIR ON, A STRONG BURNING RUBBER LIKE ODOR ENTERED CABIN ON TAXI OUT. APU BLEED AIR SELECTED OFF & ODOR WENT AWAY. INSPECTED WATER SEPARATOR IAW MM 21-51-00. LEAK CHECKED APU & BLEED AIR PLUMBING. CHECKED GOOD. FOUND APU OIL OVER SERVICED. CORRECTED OIL SERVICE IAW MM 12-11-03. RAN APU FOR .5 HOUR & OIL ODOR DISSIPATED.