Jeep Fuel Fill Issue

[sgesbeck]

This 2006 Jeep TJ 4.0 always had the issue of the gas pump NOT shutting off properly when filling. It would often have fuel splash out and run down the side. So a few years ago the fuel pump on the 2006 Jeep TJ 4.0 went bad. My son was driving the car when it quit and had to be towed to the house. It was a great opportunity to go through the troubleshooting with him as to what it could be. Anyway, we eventually determined it was the fuel pump and replaced it with the Bosch pump. Dropping the tank was a bit of a challenge because the amount of fuel still in it but we got it. However, when reinstalling the tank I broke one of the plastic connectors on the check valve that goes to the charcoal cannister. He drove it like that for a while and just ignored the check engine light for evap leaks.

Sometime in early 2023 my son and his wife told me that now the pump would cut out constantly when trying to fill. It would take forever. At the end of 2023 I retired and traded my 2018 Jeep JK Unlimited for the 2006 Jeep TJ Sport so I could have a project to work on. The first thing I did was drop the gas tank and repair the broken connector at the check valve. I used a pen barrel as an insert and J-B Weld for plastic to secure it. I then removed the fuel fill check valve and sanded down the ridges as described by many on this site. I reinstalled everything and took it to the gas station and no problems filling.

Fast forward to September 2024 and I started getting codes for minor/major vacuum leaks. I smoked the system and found the connector had failed again. I dropped the gas tank, and redid the repair. This time I used a metal insert (instead of the plastic pen barrel) and let it sit about 48 hours before I reinstalled. I smoked it again and no leaks. I cleared the code and figured everything was good.

I was doing some consulting work out of state so I was gone most of late September and October. When I went to fill the gas tank the pump kept shutting off. I think this was the first time getting gas after dropping the tank in September but not sure. Instead of continuing to fill the tank I brought it home and dropped the tank....AGAIN! I verified the check valve in the fill wasn't stuck but removed it and sanded it some more anyway. I removed the charcoal filter and made sure everything was good. I blew compressed air through it and didn't find any obstructions. I reinstalled the tank and tried to get gas and had the same issue with the pump stopping.

Next I removed the fill neck (without dropping the tank) and inspected it. It is the original fill tube and hose. I verified the vent tube wasn't pinched or damaged. I tried blowing compressed air into the rubber hose that connects the vent to the check valve where I did the repair. It seemed to be obstructed. At this point I stopped, put everything back together and decided to come here for help.

I suspect my "fix" for the check valve has this valve stuck in the up position which would prevent any air from being displaced while filling. Looking at the tank there is a vent line that comes from the engine compartment and connects to a T before the charcoal filter. I don't think this would affect anything with filling. There is a Rollover Valve (marked ROV) on the drivers side top of the tank. This line connects to the Check Valve (marked C/V) on the passenger side of the tank where I did the repair. If the Rollover Valve is stuck closed this could be an issue but also if the connection at the Check Valve is obstructed this would be a problem too. Finally there is a line that connects the vent tube on the fill neck to the Check Valve. From the Check Valve the large line (that was cracked) connects the tank to the Charcoal Filter.

My plan in the next few days after I get the tank closer to empty is to drop the tank (I'm like a one man pit crew with this now) and inspect all the lines connected to the tank. I will try to blow compressed air through the lines and see where I do and don't have obstructions. I will also try to inspect both the Rollover Valve and the Check Valve inside the tank to see if I see anything obvious. The troubleshooting hopefully will point me in the right direction.

Does anyone know if the Rollover Valve and the Check Valve can be removed for inspection? I don't think they can as it looks like the Rollover Valve would need to be pushed up and out of the tank based on the tabs I see in the photo. I know these aren't serviceable which makes me think I can't remove them. Does anyone have any other ideas on what I can try other than buying a used tank off Ebay? Any and all thoughts are appreciated!

 

[chili_pepper]

Does anyone know if the Rollover Valve and the Check Valve can be removed for inspection? I don't think they can as it looks like the Rollover Valve would need to be pushed up and out of the tank based on the tabs I see in the photo. I know these aren't serviceable which makes me think I can't remove them. Does anyone have any other ideas on what I can try other than buying a used tank off Ebay? Any and all thoughts are appreciated!

There are a number of threads here addressing stuck check valve issues, likely referencing one or both of the above.

 

[DuckNut]

I do not think either of those halves are replaceable. I also think the tube you think is obstructed is a one way valve (c/v).

I am agreeing with @chili_pepper that your issue is with the fill valve. If it is indeed something beyond that, I would be leaning toward the canister. None of those houses have much to do with the ability to add fuel. Yes, the fuel vent does vent some air but the vast majority just comes right up and out of the filler hose.

 

[sgesbeck]

There are a number of threads here addressing stuck check valve issues, likely referencing one or both of the above.

I watched those videos and that is why I sanded down the fuel fill check valve. That solved the original problem but it came back so I sanded it down again. There was a thread here where the op actually removed the fuel fill check valve completely and the pump continued to shut off with it removed. In his case he had purchased and installed an after market fuel fill neck with a slightly different vent tube design. When he reinstalled an OEM fuel fill neck the problem went away. That is what got me thinking the line from the vent tube to the Check Valve is plugged. Also I should be able to blow compressed air into the vent tube and get air flow. With no air flow it would indicate an obstruction which would then inhibit venting.

https://wranglertjforum.com/threads/magic-gas-tank-not-your-average-slow-filling-thread.80848/

The low fuel light just came on so I'll be dropping the tank tomorrow and I'll update how it goes.

 

[sgesbeck]

I do not think either of those halves are replaceable. I also think the tube you think is obstructed is a one way valve (c/v).

I am agreeing with @chili_pepper that your issue is with the fill valve. If it is indeed something beyond that, I would be leaning toward the canister. None of those houses have much to do with the ability to add fuel. Yes, the fuel vent does vent some air but the vast majority just comes right up and out of the filler hose.

The tube that I believe is obstructed should allow

I do not think either of those halves are replaceable. I also think the tube you think is obstructed is a one way valve (c/v).

I am agreeing with @chili_pepper that your issue is with the fill valve. If it is indeed something beyond that, I would be leaning toward the canister. None of those houses have much to do with the ability to add fuel. Yes, the fuel vent does vent some air but the vast majority just comes right up and out of the filler hose.

Thanks for the feedback. I will be dropping the tank tomorrow and I'll report back what I find. I read another thread where the OP completely removed the fill check valve and he still couldn't get the pump to not shut off. It turned out it was the design of the aftermarket vent tube he got from TRQ. When he installed an OEM fill neck the problem was resolved. That's what made me start suspecting the vent lines since I still have the original fill neck.

https://wranglertjforum.com/threads/magic-gas-tank-not-your-average-slow-filling-thread.80848/

 

[sgesbeck]

Update: I was able to resolve the issue. The Check Valve on the passenger side of the tank (not the fuel fill neck check valve or plunger as some describe it) was fine but the connection from the check valve to the charcoal cannister was obstructed. In the photo there are two smaller lines coming into the Check Valve on the right side. One line comes from the fill neck and the other comes from the Rollover Valve. On the opposite side of these connections is the larger line that goes to the charcoal cannister. This is where I had done a repair using J-B Weld for plastic on the connector. I got some material in the barrel that I used to join the pieces (like a large roll pin) and this was restricting the venting of the tank. I can't believe I did that....pretty embarrassing really. Cleared everything out and rejoined the connection with J-B Weld again and let it sit overnight. This morning I reinstalled everything and filled the tank without any issue. I even got 16.5 gallons in without any of the old splash back issue.

I hope this helps someone else down the line. While the fuel fill check check valve or plunger was the original issue a year ago and is typically the most likely root cause of the gas pump shutting off, there are other things that can create the same issue.

 

[Mikegevas]

can you just delete the filler neck valve and do that by knocking it back into the tank from where the filler hose attaches to the tank with a hammer and screwdriver?

 

[Fughuert]

Update: I was able to resolve the issue. The Check Valve on the passenger side of the tank (not the fuel fill neck check valve or plunger as some describe it) was fine but the connection from the check valve to the charcoal cannister was obstructed. In the photo there are two smaller lines coming into the Check Valve on the right side. One line comes from the fill neck and the other comes from the Rollover Valve. On the opposite side of these connections is the larger line that goes to the charcoal cannister. This is where I had done a repair using J-B Weld for plastic on the connector. I got some material in the barrel that I used to join the pieces (like a large roll pin) and this was restricting the venting of the tank. I can't believe I did that....pretty embarrassing really. Cleared everything out and rejoined the connection with J-B Weld again and let it sit overnight. This morning I reinstalled everything and filled the tank without any issue. I even got 16.5 gallons in without any of the old splash back issue.

I hope this helps someone else down the line. While the fuel fill check check valve or plunger was the original issue a year ago and is typically the most likely root cause of the gas pump shutting off, there are other things that can create the same issue.

View attachment 587872

What'd you do to replace the broken plastic there? I broke mine too and also used a pen body but I suspect it is too small as I sometimes cannot fill my tank quickly.