So yesterday i installed ppe fuel releif valve shim kit on my lly duramax. I installed it put everything back together and got it running. It idled great, but when i went to road test it wouldnt rev over 2000 rpm kinda like it was in a limp mode. Ran a scan tool on it and had no codes. I expected i must have messed up the releif valve some how so i took it back off today, and it didnt seem to have a problem so i reinstalled it, now my truck wont start. Primed the system but wont go. Any ideas? I tried taking the shims back out and still no go...please help

 

Sounds like low rail pressure