Son bought a Chevy 3500 with a 6.5 in it. Has been sitting for years, previous owner said truck just quit running, took to a mechanic and he said he couldn’t fix it. We put new pmd on it , all new engine wire harnesses from the loom out, new glow plugs and harness. It will crank but there is no fuel coming out of injection pump. We installed new lift pump and have good flow to ip. We have the lines off at ip and absolutely no fuel coming out of ip. Any suggestions?