Re: That good ol\' gas smell..
The 88 YJ has no purge solenoid, the check valves are on the top of the plastic tank, and up inside the right rear fender on the steel 15 gallon tank. One of the valves are plugged, of the hose is pinched. There is not supposed to be any pressure in the tank. The vent lines are free flowing into the charcoal cannister, the charcoal absorbs the fuel vapors, the air vents to the atmosphere through the bowl vent hose. When the engine is running, the ported vacuum signal opens the vacuum port in the cannister, allowing the trapped fuel to be drawn into the PCV line to be burned. The gas cap should only allow air to enter into the tank, and hold pressure to at least 1.5 PSI.
Hope this helps, good luck!