I have a 2004 Chevy Duramax LLY 6.6 turbo diesel that will crank but wont start. Will on run ether. Checked all fuses and they are good. Checked glow plugs and are working. Injection box is working. No DTC's. Repaired wiring harness above alternator on passenger side. Replaced fuel pump filter and water sensor. Fuel rail pressures are good. Need help to figure out why it wont start.