As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU WOULD HANG AT 250-300 DEGREES FOR APPROXIMATELY 30 SECONDS DURING START AND THEN ACCELERATE. APU WAS MAKING CHUGGING EXHAUST NOISES WHEN RUNNING. SB GTCP85-49-7484 INCORPORATES A NEW FUEL CONTROL, PN 3617750-1 AND ATOMIZER/LINER ASSEMBLY TO IMPROVE START TIMES. REPLACED THE FUEL CONTROL AND ATOMIZER/LINER ASSEMBLY IAW THE SB AND AMM. APU STARTS MUCH QUICKER NOW AND NO LONGER MAKES CHUGGING NOISES WHEN OPERATING.