jamesinc Alright well I would just probe the wiring with the multimeter until you find either where you are losing your 12V or if you have a broken ground or something.
One other thought - the fuel pumps wouldn't get power unless the engine was turning and pulling air past the air metering flap, or unless you unplugged the "is the metering flap completely closed" sensor plug, and shorted the two pins together. The plug I'm talking about sits below the giant rubber boot that goes between the intake manifold and the K-Jet air box, sticks out of the side on the passenger side of the car, can't miss it. I'm pretty sure Volvo were still doing it that way in 1978. Later on they switched to a different relay that listens for ignition coil pulses to decide if the pumps should get power.
The tip re the sensor on the air metering flap was on point.. I disconnected the plug, tested resistance, removed some Crusty junk from the connector, and then when I turned it over we had fuel coming to the front. I installed the new fuel filter, but still no start. The plugs were terrible so I've replaced them, still looks like no spark. Put the multimeter over the ignition coil, get between 2 and 4 ohms - will need to look for the desired value, but a google suggests it's in the ballpark.
Next stop - distributor town.
