Thanks Jon, that certainly explains why you would get the effect from a pulled down Rx pack. I am used to separate packs for the ecu and the Rx, with the pump running from the ecu pack. The downside to that method is when the glow and starter function at the same time there can be a voltage depression. The upside is that the pump is not on at the same time as the glow plug. It seems a wider distribution of loads, but each has its own merits.

Thanks again,
Len