Skunk 316

I have an 08 wrangler with a 3.8 L motor while filling the gas tank fuel backs up and kicks off the fuel nozzle. Even if I slow it down it still is an issue. I have read where people install a larger fuel hose, and this cures the problem, but that doesn’t make sense to me. So I disassembled my fuel filler hose that attaches to the plastic neck on my fuel tank no obstructions, but what I did find was that when I blow in the plastic nozzle that is attached to the fuel tank I get pressure, when I sucked back on it, of course I got a lot of fuel vapors, but I got very little vacuum resistance. I would have thought I would’ve been able to blow with little to no resistance, and then, when I suck a valve would have stopped vacuum from being pulled from the tank (I would assume the valve at the fuel filler plastic neck connection is for if the vehicle was to turn over fuel cannot escape) also, the vent line that attaches to the fuel filler neck was removed and checked for any obstructions. None were found, I was also able to blow and suck on the plastic nipple. That’s attached to the tank for that vent line, and it seems to be working properly.
I have watched a video someone has dropped the tank, removed the fuel pump section and reached in and unlocked where the plastic neck is and pulled out the plunger spring assembly and there wasn’t enough clearance for the plunger to actuate properly, but they were also working on an 07 I just wonder if the 08 assembly has the same design?
has anyone dealt with this issue? I just don’t wanna throw parts at it without understanding it.

resharp001

So, I've dealt with this a bit recently on my '13. To the best of my knowledge, there is a slight difference in our evap canisters, but that is it. I had no reason to believe anything happened to my rollover vavle in the tank, so I focussed on the evap canister. it was clear to me the canister itself was fine cuz I could easily push air through it so it wasn't clogged. The vent from the evap control module up to the taillight cavity was clear too. I removed the control module itself from the canister (I had replaced it a couple years ago with a Dorman unit to fix a nagging P0456) and blew through it back and forth. Nothing seemed abnormal, but after doing that I was able to fill up again. One thing that was odd was when it did take fuel, i was getting kinda of an accordion funnel "gurgling" sound, for lack of better description as the fuel went it. It started refusing to take fuel on me again a few weeks later and I replaced that control module again. No issues since, though occasionally I'm still getting that venting sound.

The one thing I might suggest is that since it's easy to access, and cheap, take a look at that little module on the backside of your evap canister. Given the age, you might just make sure your evap canister itself is not clogged. After these options, I'd start suspecting that rollover valve in the tank I think.

Certainly can't say I have all the answers for you, but I've been in this boat and I know it's frustrating as hell.

Skunk 316

Thanks for the reply, I will certainly consider your recommendations! I think I’ve already replaced that module, but I will go back and look again. Our problems sound similar. I sure don’t want to get into the tank and take apart the rollover valve and start other issues. I’m afraid to touch anything to start a cascade to other issues.

resharp001

The other thing that is free to try, but a little cumbersome.....slide under the jeep and just remove that control module before you fill up and see if that makes a difference not being there. it's only 1/4 turn to pop that sucker off. That could at least eliminate it or highlight it as an issue.

Skunk 316

That’s funny you mentioned that, after reading your post this morning that was one of the thoughts running through my mind!
I will try that if no results, I think I’m going to pull off the vapor canister and test it.

resharp001

Did you make any progress troubleshooting this?

Skunk 316

I have plans on addressing it again this weekend or first of next week. I’ll post my findings.

Skunk 316

just to clarify, this picture is the pressurized pump module that I’m referring to that I removed that is actually attached to the charcoal canister

So I finally got time to put gas in the jeep, so when I get to the fueling station I removed the charcoal canister module sure enough when I started filling up the tone of the fuel in the neck never changed, and what I mean by that I could hold the nozzle wide open, and it never backed up or tried to back up . so that got me looking through my glove box, and I found the receipt to where I replaced that module in June 2023.
So now I will probably remove that module and put 12 V to it and see if it actuates, if it does, I can assume that the module is still working and the canister may be the issue. Also, in my thought process that when the vehicle is shut down, that module would be in the open state to allow the vapor canister and fuel tank to vent so back pressure wouldn’t build in the fuel neck.
And if that were the case, and that module was not changing, states, I would’ve thought some kind of code would’ve been thrown ?
Now I’m kind of wondering is maybe the module is actually working but the charcoal canister has failed? I might disconnect the lines to the charcoal canister and see if I get airflow through the canister.
I do believe if I remove the charcoal canister and hear rattling inside the canister that is an indication that it has failed. I do appreciate your input. I wasn’t looking forward to going after the tip over valve inside the tank that would’ve been a lot of trouble and a waste of time. This is much easier accessing the module and canister.
Again, thank you for your input!
Joe Mattingly

resharp001

I don't think it's the canister itself or else I think you would have had the same issue without the module in place. If it was clogged the air would not have passed through the canister and through the empty opening. That is just my logical thinking though. I had removed my canister and blew air through it to confirm it was not blocked as well.

Was your replacement a factory unit or aftermarket? I originally replaced mine with a Dorman unit few years back as that was the cause of my P0456 small evap leak code. I had no issues with that Dorman unit until couple months ago when it randomly did this. I just threw a new Dorman unit on there again and have had no issues filling up since; however, I do hear a "growl" or a noise coming from the venting when filling up. Starting to think that a factory unit might just be the only way to go for this particular component.

Skunk 316

Yes, it was a Dorman.