Congratulations on the cheap fix. Glad you resolved your issue and posted the solution.
Others on this forum (with turbos) claim they run low test gas and don't have issues. My owners manual states minimum 91 octane and the only time in 16 years I ran low test, I had issues.

Great writeup, Zeeko. I made your account MVS Contributor level. I'll put this in the Volvo Repair Database.

The 30665496 had an issue with a piece detaching inside. The 30645621 is the latest design and will do but you'll need its rubber hose to the pump as well because the two hoses are pretty different in shape. If you get a new 30665496 there should be no problem with it.