Well I'm fixed. Engine wiring harness repaired, and a new water pump while they were at it. There was a short inside the wiring harness itself, down by the engine just below and behind the fuel filter on the Sprinter. The wires wear in the harness, and laying on a bracket or some other metal shorts them out. The tech repaired the harness, put new loom and tape on it, and then tied the harness in several places away from metal. The short was blowing one of the ECM fuses under the steering column. It would blow upon acceleration, and then it wouldn't crank, nothing. It took nearly 13 hours, eliminating each sensor or electrical component that fuse feeds, to track down the exact spot in the harness where the high resistance revealed the short.
I broke down 6 miles from delivery, right in front of the entrance to the Holland Tunnel. It's an experience I highly recommend. Especially if you can do it in the aftermath of massive flooding from a hurricane when tow trucks are just fighting over who will come tow you out of there.
The folks in Dispatch, Caryn in particular, Vince and Matt in the shop, and Becky in admin, and of course John, all went above and beyond. I can't thank them enough.