If you check out the electrical issues mentioned and they don't solve the issue, might be worth measuring the fuel pressure to see if pump is weak or system is somehow not holding pressure. I had this issue on a 240 series where the symptom was need for priming and long use of the starter.

A not too bad fuel pressure gauge is avaialable at the Autozone or similar. Mine has the brand name Actron.

There is only one 'sensor' that could have an effect on the injectors or spark, and that is the cam position sensor. When the CPS goes bad, there is usually a code that gets set and the CEL may turn on.

So start looking for fuel delivery problems.

Klaus
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Why are Volvos so endearing? Its just a car.

Hi, my first bet would be unreliable fuel pump relay, which some times connects the otheer not. try to listen when turning the key to lights-on-position, the pump should run for few seconds, repeat the test.
easy to eliminate or fix by new relay, 50euro and 15 minutes work.
second bet is the key lock itself, move the key in position and listen for pump to go.
br tapsa

Have you checked for any diagnostic codes ?
From your description of "priming", it sounds like fuel delivery issues. That could be many things, including but not limited to: fuel pump, FPR, injectors, sensors.
If you could give a more descriptive account, you will get better responses.
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91 745t, 95 855t, 90 745NA (B234 not running yet), 94 854 parts car