Joined the Forum to troubleshoot my 2007 Vortec Max, Ended up fixing it by getting a 2014 Sierra Denali.
Bought a Gator EFX Yesterday for it to haul my tp dry...
Jeffery Porter,
Did you come up with anything else?
Same issue -276k mile L76 - haven't replaced pump yet. (Already did relief valve in pan, valley cover without dod/afm, new pressure switch)