tank gurgling?

[WIFEYSQX4]

did some errands yesterday and when I got to one location I smelled a strong fuel odor. Got home and when I turned the car off I went to the rear and smelled that smell again so I opened the fuel gas cap and heard this gurgling sound coming from inside the tank. this lasted for about five minutes not sure what caused this...is it a clogged evap canister or what???

[centralcoaster33]

The gas cap itself is a valve. Could need replacing. Was there a suck of vacuum as you opened it, then a gurgle as the fuel settled? If you fill the tank, run it until near empty, then go to fill it up and there's a big suction, then the gas cap valve is probably shot. There are also a series of hoses and such that spread out to fuel in the tank, sort of like siphons. Perhaps one has been disconnected. You'd have to run over something while off-roading or whatever to pull a hose off with a branch. Was there any fuel on the ground?

[WIFEYSQX4]

No fuel on ground, no disconnected hoses, when i open it there is sometimes a vaccuum suck to it but not everytime...I've noticed a drop in mpg's as well and according to my scan tool (viewing live data on the way to work) i noticed it's running rich (short term fuel trim is in the negatives)

[centralcoaster33]

I'd consider replacing the gas cap. They're affordable and they don't last forever and I don't know how to test it on my own. Maybe the SMOG guys would test it for free or cheap on their machine. I'd consider replacing the fuel filter if it's been a while since the last replacement. I'd inspect my fuel lines looking for leaks or strong gas odor along the length of them. I'd do the same for the EVAP lines. I'd test the resistance of my fuel injectors. I'd visually inspect them to see if a bad seal can be detected easily by moisture or discoloration. I'd scan for codes expecting MAF or O2 sensors (though you are using a scanner so maybe those haven't been far enough out of spec yet to toss a code). I'd clean the MAF. I'd keep driving it and taking note. I'd be interested in the strongest source of the gas smells (exhaust, cabin, engine bay).

Can you do some or all of that?

[WIFEYSQX4]

Fuel smell was really strong at the rear drivers side of the vehicle, and i believe the gas cap is oe nonvented so would that matter? Maf sensor is reading in spec too via the live data. I haven't touched the fuel filter since i purchased the vehicle 45k miles ago (currently at 166k) so I'll definitely check that. I've recently replaced the entire fuel sending unit and pump and also the vacuum cut valve.

[centralcoaster33]

The OE gas cap has a valve in it, so yes it would matter. Vented went out with the '60s. Here in CA, as part of the SMOG test, the cap is removed and tested to make sure it maintains seal with pressure, but allows air in with vacuum. So yeah, it is a working part that can go bad and need replacing. My local SMOG shop happens to stock replacement gas caps should that be the only thing causing one to fail their test. They're affordable, though I'm not one to recommend throwing parts at a situation without prior diagnoses.

Now you've added some useful information... recent repairs that directly affect the fuel system (and coincidentally are near the fuel smell). Did you use a new o-ring with your work? Can you re-do or double check that stuff? I'll put a link to the fuel chapter of the FSM that you can use to verify you did it all correctly. You might want to pull it out, check your fittings and hoses and such, then put it back, possibly with a new o-ring seal. That would be a starting point before all the other stuff. Though I do recommend a new fuel filter. You're due for one of those.

http://www.nicoclub.com/service-manual?fsm=QX4/2002/FE

[WIFEYSQX4]

I've noticed it only does the gurgling and strong fuel smell only after driving around for a while with the a/c on if i don't drive with the a/c on it doesn't do it at all

[centralcoaster33]

No fuel smell or no gurgling or none of either? Driving around with no AC on, so you have the windows down for that? That would air out the fuel smells, so it wouldn't be good diagnoses. Is that what you're doing? AC refrigerant doesn't smell like gas. If the AC refrigerant was low, it could cause the gurgling sound. An AC charging shop can fix that for you pretty quick. The fuel smell. You should figure that out. I would have guess exhaust leak, because mine does that, but it smells more like exhaust than just gas. You did a fuel pump. That just tells me it's the most likely cause of the gas smell. It's in the interior and it's directly between you and your fuel. You could try driving around significant distances, with windows up and climate control off, then have someone else from the fresh air side of things smell when you open the car door. Someone else because your nose will be desensitized to it. Basically, I'm thinking you have two separate issues because you're talking about two separate systems that aren't connected in any way (AC system and Fuel system or Exhaust system). Low refrigerant and bad gas tank seal or exhaust leak.

[WIFEYSQX4]

ok so when I drive around all day no ac on I get no gas smell anywhere. However driving around with the ac on for a while once I get out and walk around to the rear of the vehicle I get the strong fuel smell, not inside the car but outside of it. I just replaced the lock ring/o-ring for the fuel sending unit and also the fuel cap since first posting this but have not driven with the ac to check. I think it might have been over pressurized from the IAC since it wasn't venting right, however I'm not sure yet as I just did this stuff yesterday and haven't had a chance to properly test it. now my only problem is figuring out how to adjust the sending unit as my gauge is reading a little high.

[centralcoaster33]

Okay, that sounds good. New gas cap and o-ring seal should keep the fumes from the gas in the tank. The AC gurgle could mean you need a charge/ refill of refrigerant.

Has the fuel smell you refer to always been outside by the rear bumper or was it in the cabin at some point? I had no idea you were out of the car for the smells.

Now, I'm not following what you said in the second half (could be me or maybe the terminology). What do you think is over-pressured, the fuel tank or the AC system (both build and release pressure)? What is the IAC? What is the Sending Unit? What gauge is reading high?

[WIFEYSQX4]

there is no AC gurgle, the gurgle came from the tank when I opened the gas cap. Fuel smell has always been outside the vehicle, never an issue with it inside the vehicle. The IAC or idle air control valve causes the engine to idle higher while the AC is running and that is why I believed due to the higher idle it was causing the fuel tank to over pressurize. The sending unit is that entire unit that is connected to the fuel pump that also contains the fuel level float and potentiometer. It appears to be adjustable with a little switch at the bottom of the potentiometer. The gauge in reference is my fuel gauge. It appeared to be reading high but after filling the tank when it got just before the light should turn on it took 17 gallons which is about where it should've been. Sorry for any confusion I may have caused with my poor word choice and/or terminology. I really appreciate the input I've received.

[centralcoaster33]

Ah! Great re-explanation. I follow. I'm not sure about the issue, but I have an idea. Have you looked at your fuel return line? Is there a chance it wasn't put back in the proper place? I see you have a vent tube, a recirculation line, a signal line and it appears to be a couple of fuel hoses to and from the pump. Instructions are to match mark the hoses so you don't mix them up. Perhaps you can spend like a half hour and double check all of those tubes, hoses, lines (whatever they're called) according to the FSM FE chapter (here's the link again http://www.nicoclub.com/service-manual?fsm=QX4/2002/FE). Also, you could look into the EVAP system. Perhaps something is not working correctly there, though I'd almost expect a code to be on the ECU causing a check engine light. Anyway, the EVAP is related to the fuel system. The FSM has the EC chapter and the EVAP system is described starting at page 341.
http://www.nicoclub.com/service-manual?fsm=QX4/2002/EC