EGR Cannister connections question

Hello XJ folk,
'91, 4.0, aw4, np231. I have been chasing poor gas mileage and low power issues. I was looking at my charcoal filter cannister thing that is close to the firewall on the passenger side an I wasn't sure if there was supposed be hoses connected to all the ports because it looks like there is a port on the bottom without a hose connected.

Any help is appreciated. If someone else has a '91, go look and let me know if there is something supposed to be connected there.

No 91 but a 90, my charcoal can has two hoses to it. One is a fat vacuum hose. That's the vacuum source. The other is a typical vac hose (~1/4"~) with a metered orofice - .024? The smaller line tees off to the rollover valves (vents) on top of the gas tank.

I have not witnessed any big hole or unconnected lines.

the canister has nothing to do with your poor milage, when was the last time you did a full tune up, what size tires and gears you running?

ROBZ95Xj said:

the canister has nothing to do with your poor milage, when was the last time you did a full tune up, what size tires and gears you running?

Click to expand...

^ this.

how many miles have you put on it since you've owned it? o2 sensor on an OBD1 jeep is the usual suspect if you don't know the last time it was changed, along with a busted vacuum line as a close second.

I don't know crap about the EGR system and thought I might have a missing hose that lead to a vacuum leak. It sounds like there is not supposed to be a hose connected to the port in question on the cannister thing pictured so thanks for clearing that up.

As for my poor mileage, I changed the O2 sensor probably six months ago. My gears and tire size haven't changed in 10 years. This thing used to get ~17mpg and now it gets ~12. I gave it a full tune up a couple months ago as well. Neither the tune up or the O2 sensor made an impact. My Jeep does run too cool and I'm pretty sure that is the mileage problem culprit. I just saw the port in the picture:

and thought I might have a hose or something missing. Thanks for the help everyone.

The evap canister is not part of the EGR (exhaust gas recirculation) system. The evap canister absorbs gas fumes from the tank and then burns them while the engine is running and will not hurt or help you gas mileage. My 93 has a vacuum line on it, one from the gas tank and one to the filter box (the one it looks like your missing).

Upon further investigation, I do have three lines; vacuum connected to the intake manifold, larger line connected to the intake box, and a third line you can barely see in the picture that I assume is connected to the gas tank. I guess there is not supposed to be anything connected to the bottom port in the picture.

if your jeep is running to cool try swapping the tstat, factory is 195, then go from there

Oh man, I've been through about 5 different 195º thermostats. I'm pretty sure the problem is with the head gasket. I've replaced pretty much everything else that could possibly be the problem.