Haven't had this type of injection on a driver in 30 yrs and the long term solution is the painless Weber 2 bbl downdraft Carb conversion(reasonable used) ,or some decent SU-HS6 carbs. You can save all the fuelie pieces for the next owner.
Back then, I got stranded w/ the '73 164....no start. Called a friend and learned there is a relay on rt, fenderwell that's sole purpose was to give a pulse to fuelpump--to squirt a shot of fuel, all injectors, to start car---and turn off. relay failed, I put a jumper wire across relay, pump started, motor started and ran. Another Volvo fuelie incident.

Good luck and Merry Christmas from Sunny Florida,cold today @ 71

Kayo,"TOO Much Steel" '57 444 Norway,'59 445,'73 142,'89-780V8,3-544.4parts