It wont start!!
 

so we replaced all the gaskets from the head up on my 06 3500 as well the injectors. We put it all back together and now we cant get it to start...we have been cranking on it for almowt 2 days straight now it will fire for about a second or 2 but then it acts like you shut off the fuel. we have checked all the intake sensors, replaced the fuel filter, checked the return pressure, and replaced the crankshaft position sensor, and still will not stay running. I would really appreciate any advice...as me and my dad are not all that good with non mechanical engines.

Do you have fuel up to the CP3? Is the pump on? double check your cross over tubes for the injectors a leak there will cause this! The system is self priming!