Finally finding time to tinker with the XM818.
With new batteries in her all the electrical seems A-OK. Even confirmed she has power to the Fuel Solenoid. So now chasing the fuel system.
The EMERGENCY Fuel Cut-Off Cable and Valve are both functioning properly and I've confirmed the Fuel Cut-Off Valve is in the "Run" position.
Primer Pump would hardly budge the Fuel Pressure Gauge's Needle, so I replace the Primer Pump's O-Rings. Now the Primer Pump will make, BUT NOT HOLD 30 P.S.I. with vigorous pumping..... Looks like it's on to the Selector Valve and Rubber Hose inspection/replacement as my next indicated step(s).
THANK YOU for the wealth of information archived in this thread. More on this as we progress towards "The Shepherd's" RESURRECTION !!!