The other day, after the car sat in the sun for about an hour, and then driving about an hour home, I noticed gurgling in the back and there was a lot of pressure when I unscrewed the gas cap (it was REALLY hard to unscrew, too).

In the FSM, for my 87, page 6E3-C3-1, it talks about a fuel tank pressure control valve, but I can't find out where it's located. On top of the fuel tank?

Pressure release is normal when you open the cap.

There is an evap system with a charcoal canister located in the front of the engine compartment near the ds headlight. Might be what you are referring to. There are tests in the FSM if you are concerned about it.

Hmmm... the drawing on page C3-3 shows a Tank Pressure Control Valve separate from the Solenoid (which is next to the canister) and the Purge Control Valve (which is ON the canister).

Please read the page 6E3-C3-2. It describes the "fuel tank pressure control valve" as an in-tank spring-biased vacuum operated diaphragm valve. Hope that helps.

This is from my 89 FSM. I hope it matches.

Attached.

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I am of the mindset that the gurgling and pressure have everything to do with the evap system.

I would focus on that.

Thanks for the info from the 89 FSM... the 'in-tank' part is not in the 87 manual (they must have figured out it would be helpful to add it!).

I suspect something is up with the EECS, as well, so I'll try looking at that again (I tried months ago, but didn't find anything wrong).

Cheers!

I have the 1987 service manual... let me check what I can find.