totally stumped 7.3

[chuie842]

I just started with a new company and my current project is killing me . I've been a diesel mech for 15 years so I'm not new at this . I have a 03 f450 with the 7.3 it had a tuner on it before I started and they melted down #5 cylinder, I pulled the engine and happened to have a donor out of a 96 so I pulled them down and rebuilt the short block on the 96 . I kept the front cover off the 96 put the engine in the truck and had a major oil leak at the hpop reservoir . I later learned from you guys that if you use the new gasket and the old cover then you crack the front cover ..... **** me right ? So I replaced it in the truck without lifting the cab .... yes you can do it but then that's where the trouble starts .The truck idles great how ever when you rev it up the oil pressure gauge drops then the engine dies. This is I believe due to the high pressure res going dry. I verifyed this by pulling the plug after it died it was empty . I put a manual gauge on it I only have 20 psi at idle would be OK on a old motor but this one is fresh . So I put on a new lpop, still the same , I have also replaced the cam sensor , high pressure pump ICP, IPR and fuel pump. I then removed all 8 injectors and checked the orings again now I'm out of ideas ..... could I have done something wrong with the front cover any input would be appreciated

[northern1]

i have seen many posts about the high pressure res. going dry but never seem to read an explanation...what did you find?

[chuie842]

I haven't found anything yet I think I need to pull the front cover again and look for this plug that may or may not be in it . I don't remember it when I bought the new one

[NoRalPh]

There should be a plug in the top of the res (allen key, rt side as you look back from the bumper) and if you take the "long side" of the allen key and dip it in you should find oil at @1" down. If it's running empty, that means the LPOP (engine oil pump behind the balancer) isn't keeping it supplied with oil.