The saga continues. After I swapped out the OVP relay with the one from my 350SDL, the engine cranked and ran. See above.

Went out the next morning and made the final set on the EHA and got the DP to 0.4 bar, per spec. Button everything up and fire the engine off again. Fires right off. Bring it up to 2,000 rpm and let it come to full temp, just under 80c. Back off the throttle to idle and it settles at 800 rpm. Shut engine down, crank, and repeat three times. Slept the best I have in a long time.

Got up this morning, go out, and I'm right back where I started. The engine will fire, runs a few seconds then dies. If I really work the throttle just right, I can get it above 400/500 rpm. The engine runs well at 2,000 rpm. Get it to operating temp, back off the throttle and the idle comes back to 400 rpm, sets there and shutters like it just short of shutting down, and the engine will not accelerate. From all of my readings, this indicates a bad OVP relay. Swapping out a suspect one, with an assumed good one, results in a solved problem. What am I missing here?

I expected to have to rebuild/replace most of the fuel system. There is just too much info on the issues on the web to not know. But my research has led me to believe that most, if not all, are just normal maintenance.

I keep reading about the relays having a high failure rate. How much truth do you find in the claim?