Brad could it be fuel related? And if you think it is the glow plugs I would recommend removing them all and bench testing them. I use Ac Delco 13 G glow plugs and replace glow plugs as they fail. Seldom do I just all out replace all 8 unless a customer or vehicle requires I do that. Good Luck. Report back.Rick,
In your experience is it actually necessary to replace a resistor(s), or just simply make sure wires/connections are in good shape?
I've been having an intermittent cold start issue on my '84 M1028 - sometimes hard to start in colder weather with extended cranking and/or cycling of the glow system - and so have replaced glow plug controller card, glow plug relay, and glow plugs (AC60G's), which helped a bunch, but thinking the resistors are the last point in the system to the intermittent cold start issue.