got the same problem with my 84 928, starts when it it wants to. loose all power to my headlights and fuel pump
car has no pwer to fuel pump or head lights, some times it starts, runs for a while fine, than wont dtart at all
There is ONE wire under the dash, somewhere, that if it is loose will cause the car to loose power to everything. Ma had this problem with her 1990 Volvo. The dealer reconnected and secured it and no problem. I am not sure what colour it is, but it is there.
The likely suspect is a Relay, fuse box is in the passenger compartment footwell. Hopefully you have the diagram that tells which relay is which; mine's an '86 and think they're different. As for the starting problem, mine did that a while ago and the cluprit was one of the wires to the fuel pump. The rubber came of one and would ground out sometimes.