As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI LH. ENGINE BLEED VALVE STUCK CLOSED AFTER ENGINE START. AC RETURNED TO BLOCK AND GROUNDED BY MAINTENACE .REMOVED AND REPLACED LEFT ENGINE PRSOV IAW B767 AMM 36-11-09 OPS CHECKS GOOD AFTER ENGINE RUNS..AC RETURNED TO SERVICE.