So, I’m now the proud owner of a 96 850se wagon with a b5254s, model with the fuel pressure reg underneath next to the fuel filter

My question is, why on earth does the fuel pressure regulator get it’s vacuum reference from the evap purge line, which more than likely almost never sees a vacuum state due to being the line that runs from the fuel tank to the charcoal canister, so feeds built up tank pressure rather than being under vacuum, all of the vacuum within the line is regulated by a solenoid on the radiator fan between the inlet manifold and the charcoal canister

A normal fuel system requires a pressure reg to keep the pressure at bay, so the injectors aren’t feeding total pressure at idle, yet I can take the vac line off at my fuel pressure reg and there’s no vacuum what so ever

I’m wondering if this possibly has anything to do with what seems like a high-ish fuel usage (I can’t get a proper L per distance due to odometer not working, but definitely chews on highway driving when it’s meant to be a lot better)

I've replaced the faulty o2 sensor, fuel filter, plugs, cleaned up the distributor electrodes and renewed the vac lines that were falling apart, but still can’t work out the pressure regs setup, I’m getting close to just running a separate vac line to the reg, from the manifold, to see if that helps, but not sure if that’ll lead to leaning the system right out