We frequently go through these issues with the 7.3L's . My first starting point would be disconnect both batteries, Use a high quality Battery tested such as a Snap-on VAT. Check the battery for bad cell's and CCA. Clear the codes and drive through a few drive cycles and let us know what you see as far as codes! You could have a Low Pressure Issue, You'll need a good scanner to compare oil pressure and ICP pressures and such, I'm going to upload a trouble shooting sheet if I can find it! PS, Check your Lift pump!
Last edited by mysterync; 09-16-2008 at 03:18 PM.