I've recently "completed" a major overhaul on my wiring. Everything checks out fine except the fuel sender wire has an oscillating 12V - 0V about every second with the ignition switch ON. Is this normal ? It's almost like it is on a flasher, but all the left, right and hazard wires check out fine (and a load is needed to make an old flasher "flash" anyway). Worst case is I have only one issue to deal with, much better than multiple wiring issues. Thanks!
I think I have answered my question. I found this on a 1970's era ford truck site: The fuel sending unit operates off a 5-volt pulse supplied by the instrument panel voltage regulator (IPVR, Fig. 5), so just running a 12V hot wire to the unit won't work, and in fact will fry the sending unit. Figure 5 Amazing this old stuff still works after 40+ years!
