Checking rail pressure while cranking

[Waterloo]

Just hearing your symptoms, are you sure it is fuel related? Could be the starter, or the ECM is a bit long in the tooth and in need of replacement. Have you gotten under the truck and inspected the wiring to the starter? How old is the starter? Then the ECM, run the truck, get her warmed up and smack the ECM with a screw driver handle or rubber mallet... Something I would do before tearing apart the fuel system... Is there a Davco unit on the truck, may want to inspect the o rings, change out the filter and clean the bowl... Something else to look at.