Duramax Diesel

My 2003 silverado 2500 hd duramax diesel is having trouble starting. It cranks ok but will not start until the 5th or 6th time trying. It has been at my local chevy garage now for 4 weeks. They can not figure it out. I have talked to general motors and they want the dealer to try and solve the problem. So far everything they have tried is not working. I am curious if anyone else has had a similiar problem. They have replaced fuel filter and check valve. They have checked injectors etc. Any suggestions would be appreciated.

Does that engine have glow plugs? Have they tried to replace those?

Glow plugs, fuel delivery, compression pressure. That’s what makes Diesels start or not start…How many miles on the engine?