Ok, so the buzzing and relays were nothing, all is well on that. As we moved through the possible fuel issues, we found two items:

A. It seems like no air is being pulled through the intake
B. The injectors are moving no gas

What could be the problem? The whole issues started at interstate speed - wagon engine just shuts off - now will crank, try to start, but never catch.

Fuel pumps are humming along, fuel filter is new, sparks are there.

Any ideas?

 

The timing belt may have jumped or stripped teeth.Inspect and check marks. What method did you use to determine lack of injector output?

 

Coffee can - nothing came out into it

 

You lifted the sensor plate with the key on and the injectors pulled?

 

We did last night - so now even more excitement. The ignition was squirrelly when I got it - I would start the car, then nudge the key back just a few mms in order to turn on the radio, heat, wipers etc.

That manifested last night into where I would have to position the key juuuust right in order to hit the connection to make the fuel pumps switch on as my father-in-law lifted the sensor plate. Still no gas shot out. Injectors are clean. Any suggestions?

 

One of my Volkswagens had a plugged screen in the fuel inlet banjo at the fuel distributor, but I do not know if the Volvo has that screen. First check for any leakage or blockages in the fuel line in total.

I think you should begin testing fuel pressures next. You can "rent" a pressure tester at a local parts store for a deposit. Make sure it has a banjo adapter such as the one here:

OEM/Fuel pump diagnostic kit (27167) | Fuel Pump Diagnostic Kit | AutoZone.com

Test the line pressure by connecting a fuel pressure gauge with a 3- way connector between the fuel distributor line and the control pressure regulator. Turn the ignition key to "on" and detach the electrical plug from the airflow sensor to start the pump. Pressure should be 65- 75 psi.

Here's a vid. that shows that setup (on a Delorean). It's the same thing.