2001 Odd No Start Condition

[zeppelingto]

I recently purchased a 2001 7.3. When I bought it the truck was running rough, but the price was right and the truck always started when I looked at it. A few days later the owner dropped it off. The next day I started it and moved it so I could check it out later. Few days when by and the truck wouldnt start engine sounded like it was knocking from lack of fuel. After trying for a couple the truck started. Next day I went out to start it and it knocked like it wasn't getting fuel no start.

After looking around I suspected loose UVCH and took the valve cover off. Sure enough it was loose. Tightened that up and the truck started up. Next day I drove 2 hours straight no problems with the truck. Few days went buy and same no start lack of fuel knock. The whole time the oil pressure gauge read above the middle. RPM gauge moved just a little, and fuel is 3/4 way full.

After the trip I pulled the driver's side UVCH off again and found one of the connectors to the injectors was broken so I replaced the harness. Then I checked the passengers side and found one loose connection and fixed that. Tried to start the truck and same problem.

Buzz test through my AE said 4 and 6 were low and had code for bad IDM. I swapped out the IDM with another truck and the engine started right up. Contribution was low for 3 and 8, but the truck has plenty of power. So I got a different IDM from a parts truck and plugged it in now no start. Scanned again no codes buzz test was fine.

Then I replaced the glow plug relay just since it was old. Tried to start the truck and it fired right up. Next day same problem.

So I cleaned every connection and put electrical grease on it. Still wouldn't start.

I unplugged the ICP and tried to start it no luck. I cleaned the connection added some grease and plugged it in. Now I scanned of and it says low circuit for the ICP. When I crank now the oil pressure gauge doesn't move... I check the HPOP reservoir and it had no oil. I filled it up and still no start.