A small hose dangles near the main fuel pump with a bolt securely clamped in its end. The other end of this hose is the fuel tank pressure relief port in the sender unit (short pipe). It is apparent the guy who changed the accumulator for the previous owner put the screw in this hose, because the tie wraps he used are distinctive.

The only reference to this I can find in the manual is one in the "theory" section suggesting it should connect to a "balance valve" along with the evap line from the filler pipe. That line runs through a check valve hidden in the trunk, but then proceeds uninterruped to the charcoal canister.

Symptoms: Pressure build-up in fuel tank on warm days. Emissions test paper had cryptic comment noted in fuel cap section.