It has been a long time since I worked on the 940 my late MIL drove. Nearly 20 years. The "gizmo" I found and puzzled over seems best explained as a device to smooth out the rapid pulsations inherent in the positive pressure roller pump. It seems too small to maintain rest pressure over the volume of the fuel delivery plumbing.

If I had your symptoms, that is, needing to run the pump for a length of time in the morning before cranking, I'd look into how the fuel pressure regulator maintains rest pressure. I know it is awkward to get a gauge to attach to the Regina fuel rail, but this is your diagnostic approach short of swapping parts.

Another way for rest pressure to leak is via injectors flooding the intake manifold and whichever cylinder is open to it during rest. Either condition, fuel returning to the tank or flooding the manifold, will cause long crank times, but the leaky injector(s) will add the symptom of rough running at first.

Notes on Replacing a Regina Fuel PUmp and Why
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Art Benstein near Baltimore

"In the midst of winter, I finally learned that there was in me an invincible summer." -Albert Camus